oshmem: Update config code to match OMPI usage

enable_oshmem holds the result of a customer decision and, like
most user options, can have the values "yes" (user wants us to
build feature), "no" (user wants us not to build feature),
"" (user wants us to figure it out), and "<something>" (user
wants us to build feature, with <something> turned on).

This change updates oshmem to not lose this data by not overwriting
enable_oshmem with a yes/no and leaving the original customer
intent in place.  Aside from fixing one bug (below) there are no
customer visible changes in this patch, but it makes it possible
to do the right thing in the upcoming work to allow oshmem to be
disabled based on test results.

There was a cosmetic bug in the existing code where specifying
a feature argument (like --enable-oshmem=awesome) would result
in the "checking if want oshmem" test reporting no, but oshmem
being built anyway.  With this cleanup, the "checking if want
oshmem" test, the final output summary, and what actually happens
will all match.

Signed-off-by: Brian Barrett <bbarrett@amazon.com>

config/oshmem_configure_options.m4

@@ -6,6 +6,8 @@ dnl Copyright (c) 2013-2014 Cisco Systems, Inc.  All rights reserved.
 dnl Copyright (c) 2014      Intel, Inc. All rights reserved
 dnl Copyright (c) 2014-2015 Research Organization for Information Science
 dnl                         and Technology (RIST). All rights reserved.
+dnl Copyright (c) 2018      Amazon.com, Inc. or its affiliates.
+dnl                         All Rights reserved.
 dnl $COPYRIGHT$
 dnl
 dnl Additional copyrights may follow
@@ -25,28 +27,23 @@ AC_SUBST(OSHMEM_LIBSHMEM_EXTRA_LDFLAGS)
 AC_MSG_CHECKING([if want oshmem])
 AC_ARG_ENABLE([oshmem],
               [AC_HELP_STRING([--enable-oshmem],
-                              [Enable building the OpenSHMEM interface (available on Linux only, where it is enabled by default)])],
+                              [Enable building the OpenSHMEM interface (available on Linux only, where it is enabled by default)])])
-              [oshmem_arg_given=yes],
+if test "$enable_oshmem" = "no"; then
-              [oshmem_arg_given=no])
+    AC_MSG_RESULT([no])
-if test "$oshmem_arg_given" = "yes"; then
+elif test "$enable_oshmem" = ""; then
-    if test "$enable_oshmem" = "yes"; then
-        AC_MSG_RESULT([yes])
-        if test "$opal_found_linux" != "yes"; then
-            AC_MSG_WARN([OpenSHMEM support was requested, but currently])
-            AC_MSG_WARN([only supports Linux.])
-            AC_MSG_ERROR([Cannot continue])
-        fi
-    else
-        AC_MSG_RESULT([no])
-    fi
-else
     if test "$opal_found_linux" = "yes"; then
-        enable_oshmem=yes
         AC_MSG_RESULT([yes])
     else
         enable_oshmem=no
         AC_MSG_RESULT([not supported on this platform])
     fi
+else
+    AC_MSG_RESULT([yes])
+    if test "$opal_found_linux" != "yes"; then
+        AC_MSG_WARN([OpenSHMEM support was requested, but currently])
+        AC_MSG_WARN([only supports Linux.])
+        AC_MSG_ERROR([Cannot continue])
+    fi
 fi
 
 #
@@ -56,7 +53,7 @@ AC_MSG_CHECKING([if want SGI/Quadrics compatibility mode])
 AC_ARG_ENABLE(oshmem-compat,
         AC_HELP_STRING([--enable-oshmem-compat],
             [enable compatibility mode (default: enabled)]))
-if test "$enable_oshmem" != "no" && test "$enable_oshmem_compat" != "no"; then
+if test "$enable_oshmem_compat" != "no"; then
     AC_MSG_RESULT([yes])
     OSHMEM_SPEC_COMPAT=1
 else
@@ -75,26 +72,21 @@ AC_MSG_CHECKING([if want OSHMEM API parameter checking])
 AC_ARG_WITH(oshmem-param-check,
     AC_HELP_STRING([--with-oshmem-param-check(=VALUE)],
                    [behavior of OSHMEM API function parameter checking.  Valid values are: always, never.  If --with-oshmem-param-check is specified with no VALUE argument, it is equivalent to a VALUE of "always"; --without-oshmem-param-check is equivalent to "never" (default: always).]))
-if test "$enable_oshmem" != "no"; then
+if test "$with_oshmem_param_check" = "no" || \
-    if test "$with_oshmem_param_check" = "no" || \
+	test "$with_oshmem_param_check" = "never"; then
-       test "$with_oshmem_param_check" = "never"; then
-        shmem_param_check=0
-        AC_MSG_RESULT([never])
-    elif test "$with_oshmem_param_check" = "yes" || \
-         test "$with_oshmem_param_check" = "always" || \
-         test -z "$with_oshmem_param_check"; then
-        shmem_param_check=1
-        AC_MSG_RESULT([always])
-    else
-        shmem_param_check=1
-        AC_MSG_RESULT([unknown])
-        AC_MSG_WARN([*** Unrecognized --with-oshmem-param-check value])
-        AC_MSG_WARN([*** See "configure --help" output])
-        AC_MSG_WARN([*** Defaulting to "always"])
-    fi
-else
     shmem_param_check=0
-    AC_MSG_RESULT([no])
+    AC_MSG_RESULT([never])
+elif test "$with_oshmem_param_check" = "yes" || \
+        test "$with_oshmem_param_check" = "always" || \
+        test -z "$with_oshmem_param_check"; then
+    shmem_param_check=1
+    AC_MSG_RESULT([always])
+else
+    shmem_param_check=1
+    AC_MSG_RESULT([unknown])
+    AC_MSG_WARN([*** Unrecognized --with-oshmem-param-check value])
+    AC_MSG_WARN([*** See "configure --help" output])
+    AC_MSG_WARN([*** Defaulting to "always"])
 fi
 AC_DEFINE_UNQUOTED(OSHMEM_PARAM_CHECK, $shmem_param_check,
     [Whether we want to check OSHMEM parameters always or never])
@@ -132,7 +124,7 @@ AC_MSG_CHECKING([if want to build OSHMEM fortran bindings])
 AC_ARG_ENABLE(oshmem-fortran,
 AC_HELP_STRING([--enable-oshmem-fortran],
                [enable OSHMEM Fortran bindings (default: enabled if Fortran compiler found)]))
-if test "$enable_oshmem" != "no" && test "$enable_oshmem_fortran" != "no"; then
+if test "$enable_oshmem_fortran" != "no"; then
 # If no OMPI FORTRAN, bail
    AS_IF([test $OMPI_TRY_FORTRAN_BINDINGS -eq $OMPI_FORTRAN_NO_BINDINGS && \
           test "$enable_oshmem_fortran" = "yes"],