Some (rare) platforms only have a #define for htonl and friends,

but not anything in libc.  Which causes an incorrect answer for
AC_CHECK_FUNCS.  Work around that by also checking for the
#define.

This commit was SVN r18730.

configure.ac

@@ -753,7 +753,32 @@ OMPI_CHECK_FUNC_LIB([dirname], [gen])
 # Darwin doesn't need -lm, as it's a symlink to libSystem.dylib
 OMPI_CHECK_FUNC_LIB([ceil], [m])
 
-AC_CHECK_FUNCS([asprintf snprintf vasprintf vsnprintf openpty isatty htonl ntohl htons ntohs getpwuid fork waitpid execve pipe ptsname setsid mmap mallopt tcgetpgrp posix_memalign strsignal sysconf syslog regcmp regexec regfree _NSGetEnviron socketpair strncpy_s _strdup usleep mkfifo])
+AC_CHECK_FUNCS([asprintf snprintf vasprintf vsnprintf openpty isatty getpwuid fork waitpid execve pipe ptsname setsid mmap mallopt tcgetpgrp posix_memalign strsignal sysconf syslog regcmp regexec regfree _NSGetEnviron socketpair strncpy_s _strdup usleep mkfifo])
+
+# On some hosts, htonl is a define, so the AC_CHECK_FUNC will get
+# confused.  On others, it's in the standard library, but stubbed with
+# the magic glibc foo as not implemented.  and on other systems, it's
+# just not there.  This covers all cases.
+AC_CACHE_CHECK([for htonl define],
+  [ompi_cv_htonl_define],
+  [AC_PREPROC_IFELSE([AC_LANG_PROGRAM([
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+#ifdef HAVE_ARPA_INET_H
+#include <arpa/inet.h>
+#endif],[
+#ifndef ntohl
+#error "ntohl not defined"
+#endif
+])], [ompi_cv_htonl_define=yes], [ompi_cv_htonl_define=no])])
+AC_CHECK_FUNC([htonl], [ompi_have_htonl=yes], [ompi_have_htonl=no])
+AS_IF([test "$ompi_cv_htonl_define" = "yes" -o "$ompi_have_htonl" = "yes"],
+    [AC_DEFINE_UNQUOTED([HAVE_UNIX_BYTESWAP], [1], 
+        [whether unix byteswap routines -- htonl, htons, nothl, ntohs -- are available])])
 
 #
 # Make sure we can copy va_lists (need check declared, not linkable)

opal/include/opal/types.h

@@ -80,7 +80,7 @@ typedef int opal_socklen_t;
 static inline uint64_t hton64(uint64_t val) __opal_attribute_const__;
 static inline uint64_t hton64(uint64_t val)
 {
-#ifdef HAVE_HTONL
+#ifdef HAVE_UNIX_BYTESWAP
     union { uint64_t ll;
             uint32_t l[2];
     } w, r;
@@ -104,7 +104,7 @@ static inline uint64_t hton64(uint64_t val)
 static inline uint64_t ntoh64(uint64_t val) __opal_attribute_const__;
 static inline uint64_t ntoh64(uint64_t val)
 {
-#ifdef HAVE_NTOHL
+#ifdef HAVE_UNIX_BYTESWAP
     union { uint64_t ll;
             uint32_t l[2];
     } w, r;
@@ -142,7 +142,7 @@ static inline void* ompi_ptr_ltop( uint64_t value )
     return (void*)(uintptr_t) value;
 }
 
-#if defined(WORDS_BIGENDIAN) || !defined(HAVE_HTONS) || !defined(HAVE_HTONL)
+#if defined(WORDS_BIGENDIAN) || !defined(HAVE_UNIX_BYTESWAP)
 static inline uint16_t opal_swap_bytes2(uint16_t val) __opal_attribute_const__;
 static inline uint16_t opal_swap_bytes2(uint16_t val) 
 {
@@ -197,6 +197,6 @@ static inline uint64_t opal_swap_bytes8(uint64_t val)
 #define opal_swap_bytes2 htons
 #define opal_swap_bytes4 htonl
 #define opal_swap_bytes8 hton64
-#endif /* WORDS_BIGENDIAN || !HAVE_HTONS || !HAVE_HTONL */
+#endif /* WORDS_BIGENDIAN || !HAVE_UNIX_BYTESWAP */
 
 #endif /* OPAL_TYPES_H */

opal/include/opal_config_bottom.h

@@ -428,20 +428,12 @@ typedef long long bool;
  * and would want to talk to the outside world... On other platforms
  * (like Windows) we fail to detect them correctly.
  */
-#ifndef __WINDOWS__
+#if !defined(__WINDOWS__) && !defined(HAVE_UNIX_BYTESWAP)
-#ifndef HAVE_HTONL
 static inline uint32_t htonl(uint32_t hostvar) { return hostvar; }
-#endif
-#ifndef HAVE_NTOHL
 static inline uint32_t ntohl(uint32_t netvar) { return netvar; }
-#endif
-#ifndef HAVE_HTONS
 static inline uint16_t htons(uint16_t hostvar) { return hostvar; }
-#endif
-#ifndef HAVE_NTOHS
 static inline uint16_t ntohs(uint16_t netvar) { return netvar; }
 #endif
-#endif  /* WINDOWS */
 
 /*
  * Define __func__-preprocessor directive if the compiler does not