Fix OSX-test in xcodeproj.

Author: inamiy

SwiftState.xcodeproj/project.pbxproj

@@ -607,6 +607,7 @@
 				INFOPLIST_FILE = SwiftStateTests/Info.plist;
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/../Frameworks @loader_path/../Frameworks";
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SDKROOT = macosx;
 			};
 			name = Debug;
 		};
@@ -621,6 +622,7 @@
 				INFOPLIST_FILE = SwiftStateTests/Info.plist;
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/../Frameworks @loader_path/../Frameworks";
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SDKROOT = macosx;
 			};
 			name = Release;
 		};