(ITS#4608) Testing for GMP broken fix

configure.in

@@ -2333,7 +2333,7 @@ fi
 if test $ol_with_mp = gmp || test $ol_with_mp = auto ; then
 	AC_CHECK_HEADERS(gmp.h)
 	AC_CHECK_LIB(gmp, __gmpz_add_ui)
-	if test $ac_cv_header_gmp_h = yes && test $ac_cv_lib_gmp = yes ; then
+	if test $ac_cv_header_gmp_h = yes && test $ac_cv_lib_gmp___gmpz_add_ui = yes ; then
 		AC_DEFINE(USE_MP_GMP,1,[define to use GMP for MP])
 		ol_with_mp=gmp
 	elif test $ol_with_mp = gmp ; then