vsyslog is not included in SUSv3. Add a check for platforms that do not have vsyslog

This commit was SVN r24339.

configure.ac

@@ -699,7 +699,7 @@ 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 getpwuid fork waitpid execve pipe ptsname setsid mmap tcgetpgrp posix_memalign strsignal sysconf syslog regcmp regexec regfree _NSGetEnviron socketpair strncpy_s _strdup usleep mkfifo dbopen dbm_open])
+AC_CHECK_FUNCS([asprintf snprintf vasprintf vsnprintf openpty isatty getpwuid fork waitpid execve pipe ptsname setsid mmap tcgetpgrp posix_memalign strsignal sysconf syslog vsyslog regcmp regexec regfree _NSGetEnviron socketpair strncpy_s _strdup usleep mkfifo dbopen dbm_open])
 
 # 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

orte/mca/notifier/syslog/notifier_syslog_module.c

@@ -82,7 +82,14 @@ static void mylog(orte_notifier_base_severity_t severity, int errcode,
                   const char *msg, va_list ap)
 {
     /* If there was a message, output it */
+#if defined(HAVE_VSYSLOG)
     vsyslog(severity, msg, ap);
+#else
+    char *output;
+    vasprintf(&output, msg, ap);
+    syslog(severity, output);
+    free(output);
+#endif
 }
 
 static void myhelplog(orte_notifier_base_severity_t severity, int errcode,