Simplify Pgrab and proc library Autoconf check (#13488)

For Solaris/illumos systems, in this case, the check can be done using
AC_SEARCH_LIBS, which avoids defining redundant symbols like HAVE_PGRAB
and HAVE_LIBPROC.

Author: petk

configure.ac

@@ -372,6 +372,9 @@ case $host_alias in
     ;;
 esac
 
+dnl Solaris/Illumos for process mapping.
+AC_SEARCH_LIBS([Pgrab], [proc])
+
 dnl Then headers.
 dnl ----------------------------------------------------------------------------
 
@@ -644,9 +647,6 @@ AC_CHECK_FUNCS([nanosleep],,
 dnl Haiku does not have network api in libc.
 PHP_CHECK_FUNC_LIB(setsockopt, network)
 
-dnl Solaris/Illumos for process mapping.
-PHP_CHECK_FUNC_LIB(Pgrab, proc)
-
 dnl Check for getaddrinfo, should be a better way, but... Also check for working
 dnl getaddrinfo.
 AC_CACHE_CHECK([for getaddrinfo], ac_cv_func_getaddrinfo,