Examples/test: enforce c99 for GCC-based compilers included with older Xcode releases

Examples/test/test.xcodeproj/project.pbxproj

@@ -216,6 +216,7 @@
 					"$(FRAMEWORK_SEARCH_PATHS_QUOTED_FOR_TARGET_1)",
 				);
 				FRAMEWORK_SEARCH_PATHS_QUOTED_FOR_TARGET_1 = "\"$(SRCROOT)/../../build/Debug\"";
+				GCC_C_LANGUAGE_STANDARD = c99;
 				GCC_DYNAMIC_NO_PIC = NO;
 				GCC_ENABLE_FIX_AND_CONTINUE = YES;
 				GCC_MODEL_TUNING = G5;
@@ -247,6 +248,7 @@
 					"$(FRAMEWORK_SEARCH_PATHS_QUOTED_FOR_TARGET_1)",
 				);
 				FRAMEWORK_SEARCH_PATHS_QUOTED_FOR_TARGET_1 = "\"$(SRCROOT)/../../build/Debug\"";
+				GCC_C_LANGUAGE_STANDARD = c99;
 				GCC_GENERATE_DEBUGGING_SYMBOLS = NO;
 				GCC_MODEL_TUNING = G5;
 				INFOPLIST_FILE = Info.plist;