configure: Don't try to detect clang by $CC

Only check if option -Werror=unknown-warning-option is supported before adding it

diff --git a/configure b/configure
index 52871c43c7959cf2ab02c06d6d443238a7137aab..f7b14d9d9730d9830e132e5d8ab50b7a3c066400 100755 (executable)
--- a/configure
+++ b/configure
@@ -589,7 +589,7 @@ else
     fi
 fi
 
-if [[ "$cc_base" = clang* ]]; then
+if [ $compiler = GNU ]; then
     if cc_check '' -Werror=unknown-warning-option ; then
         CHECK_CFLAGS="$CHECK_CFLAGS -Werror=unknown-warning-option"
     fi