unbreak with clang, no reason to insist on gcc

graphics/krita/patches/patch-plugins_extensions_CMakeLists_txt

@@ -0,0 +1,14 @@
+$OpenBSD: patch-plugins_extensions_CMakeLists_txt,v 1.1 2017/06/04 18:06:28 espie Exp $
+clang is happy building this
+
+Index: plugins/extensions/CMakeLists.txt
+--- plugins/extensions/CMakeLists.txt.orig
++++ plugins/extensions/CMakeLists.txt
+@@ -19,7 +19,5 @@ add_subdirectory( waveletdecompose )
+ # Allow to skip building GMIC plugin
+ option(WITH_GMIC "Build the G'Mic plugin" ON)
+ if(WITH_GMIC)
+-if (CMAKE_COMPILER_IS_GNUCC)
+     add_subdirectory( gmic )
+-endif()
+ endif()