Enabled 'Require only App-Extension-Safe API' build setting for both framework targets.

Masonry.xcodeproj/project.pbxproj

@@ -343,6 +343,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
+				APPLICATION_EXTENSION_API_ONLY = YES;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
 				CLANG_CXX_LIBRARY = "libc++";
 				CLANG_ENABLE_MODULES = YES;
@@ -391,6 +392,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
+				APPLICATION_EXTENSION_API_ONLY = YES;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
 				CLANG_CXX_LIBRARY = "libc++";
 				CLANG_ENABLE_MODULES = YES;