libevent2022: Fix broken configure AC_LANG_PROGRAM

 * Similar to commit 029964a
   This removes an extra `int main` during configure.

Signed-off-by: Joshua Hursey <[email protected]>
(cherry picked from commit 72ac812)
Signed-off-by: Joshua Hursey <[email protected]>

Author: jjhursey

opal/mca/event/libevent2022/libevent/configure.ac

@@ -668,9 +668,6 @@ AC_INCLUDES_DEFAULT
 #include <sys/syscall.h>
 #include <sys/epoll.h>
 ],[[
-int
-main(int argc, char **argv)
-{
     struct epoll_event epevin;
     struct epoll_event epevout;
     int res;
@@ -699,7 +696,6 @@ main(int argc, char **argv)
         }
     }
     /* SUCCESS */
-}
 ]])],
         [haveepollsyscall=yes
         # OMPI: don't use AC_LIBOBJ