Remove spurious argument to AC_CHECK_ALIGNOF, which caused this
configure test to fail.

Submitted upstream: <https://github.com/pmodels/mpich/pull/6302>

diff --git a/configure.ac b/configure.ac
index 3e2aa2cb7e828675..f76eb49833bb358c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2701,7 +2701,7 @@ if test "$MPID_NO_FLOAT16" != "yes" ; then
 fi
 
 # ----------------------------------------------------------------------------
-AC_CHECK_ALIGNOF([max_align_t],[0],[#include <stddef.h>])
+AC_CHECK_ALIGNOF([max_align_t],[#include <stddef.h>])
 
 if test "$ac_cv_alignof_max_align_t" != "0" ; then
     AC_DEFINE_UNQUOTED(MAX_ALIGNMENT,$ac_cv_alignof_max_align_t,[Controls byte alignment of structures (for aligning allocated structures)])