Fix ROMIO use of PATH_MAX.

We need to discover the existence and then include sys/param.h while
using the correctly named MPL defines.

Fixes #12108

Signed-off-by: George Bosilca <bosilca@icl.utk.edu>
(cherry picked from commit 9347a55)

3rd-party/romio341/mpl/configure.ac

@@ -138,7 +138,7 @@ if test "$pac_cv_have___typeof" = "yes" ; then
 fi
 
 dnl Check if the necessary headers are available
-AC_CHECK_HEADERS(stdio.h stdlib.h string.h stdarg.h ctype.h sys/types.h sys/uio.h execinfo.h unistd.h errno.h windows.h sys/mman.h)
+AC_CHECK_HEADERS(stdio.h stdlib.h string.h stdarg.h ctype.h sys/types.h sys/uio.h execinfo.h unistd.h errno.h windows.h sys/mman.h sys/param.h)
 
 # A C99 compliant compiler should have inttypes.h for fixed-size int types
 AC_CHECK_HEADERS(inttypes.h stdint.h)

3rd-party/romio341/mpl/src/str/mpl_str.c

@@ -6,15 +6,19 @@
 #include "mpl.h"
 #include <assert.h>
 
-#ifdef HAVE_UNISTD_H
+#ifdef MPL_HAVE_UNISTD_H
 #include <unistd.h>
 #endif
 
-#ifdef HAVE_SYS_TYPES_H
+#ifdef MPL_HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif
 
-#ifdef HAVE_TIME_H
+#ifdef MPL_HAVE_SYS_PARAM_H
+#include <sys/param.h>
+#endif
+
+#ifdef MPL_HAVE_TIME_H
 #include <time.h>
 #endif