Check for MX library and output the corect error message. This function is now shared between

the MX BTL and MX PTL, so I decide to have short common options on the "configure --help".
--with-mx = for the base MX directory and
--with-mx-libdir = for the library path.

This commit was SVN r6631.

config/ompi_check_mx.m4

@@ -54,11 +54,12 @@ AC_DEFUN([_OMPI_CHECK_MX_CONFIG],[
 # LDFLAGS, LIBS} as needed and runs action-if-found if there is
 # support, otherwise executes action-if-not-found
 AC_DEFUN([OMPI_CHECK_MX],[
+    help_name=`
     AC_ARG_WITH([mx],
-                [AC_HELP_STRING([--with-btl-mx=MX_DIR],
+                [AC_HELP_STRING([--with-mx=MX_DIR],
                                 [Additional directory to search for MX installation])])
     AC_ARG_WITH([mx-libdir],
-       [AC_HELP_STRING([--with-btl-mx-libdir=IBLIBDIR],
+                [AC_HELP_STRING([--with-mx-libdir=MXLIBDIR],
                                 [directory where the MX library can be found, if it is not in MX_DIR/lib or MX_DIR/lib64])])
 
     AS_IF([test ! -z "$with_btl_mx" -a "$with_btl_mx" != "yes"],