kde4-base.eclass: don't perform gcc version check with clang

Gentoo-bug: 587998

eclass/kde4-base.eclass

@@ -616,7 +616,7 @@ kde4-base_pkg_setup() {
 	# In theory should be in pkg_pretend but we check it only for kdelibs there
 	# and for others we do just quick scan in pkg_setup because pkg_pretend
 	# executions consume quite some time (ie. when merging 300 packages at once will cause 300 checks)
-	if [[ ${MERGE_TYPE} != binary ]]; then
+	if [[ ${MERGE_TYPE} != binary ]] && tc-is-gcc; then
 		[[ $(gcc-major-version) -lt 4 ]] || \
 				( [[ $(gcc-major-version) -eq 4 && $(gcc-minor-version) -le 6 ]] ) \
 			&& die "Sorry, but gcc-4.6 and earlier wont work for some KDE packages."