make watchkit optional to not crash on iOS 7

VLC for iOS.xcodeproj/project.pbxproj

@@ -202,7 +202,7 @@
 		7D27EC3219DF314F00EF0370 /* wifi@3x.png in Resources */ = {isa = PBXBuildFile; fileRef = 7D27EC2F19DF314F00EF0370 /* wifi@3x.png */; };
 		7D27EC3519DF315E00EF0370 /* browser.png in Resources */ = {isa = PBXBuildFile; fileRef = 7D27EC3319DF315E00EF0370 /* browser.png */; };
 		7D27EC3619DF315E00EF0370 /* browser@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = 7D27EC3419DF315E00EF0370 /* browser@2x.png */; };
-		7D298F441AD5827E00A0BF68 /* WatchKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = DDF157B31ACB169B00AAFBC6 /* WatchKit.framework */; };
+		7D298F441AD5827E00A0BF68 /* WatchKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = DDF157B31ACB169B00AAFBC6 /* WatchKit.framework */; settings = {ATTRIBUTES = (Weak, ); }; };
 		7D298F451AD58A0700A0BF68 /* UIImage+Blur.m in Sources */ = {isa = PBXBuildFile; fileRef = 7D168F7318D4A33F003FAF59 /* UIImage+Blur.m */; };
 		7D2A34A41805CDBA004078AA /* gradient-cell-ios7.png in Resources */ = {isa = PBXBuildFile; fileRef = 7D2A34A21805CDBA004078AA /* gradient-cell-ios7.png */; };
 		7D2A34A51805CDBA004078AA /* gradient-cell-ios7@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = 7D2A34A31805CDBA004078AA /* gradient-cell-ios7@2x.png */; };