Fixed error in getArguments for Mac and Linux

gameplay/src/PlatformLinux.cpp

@@ -1441,7 +1441,7 @@ namespace gameplay
     {
         if (argc)
             *argc = __argc;
-        if (arv)
+        if (argv)
             *argv = __argv;
     }
 

gameplay/src/PlatformMacOSX.mm

@@ -1794,8 +1794,10 @@ void Platform::getAccelerometerValues(float* pitch, float* roll)
 
 void Platform::getArguments(int* argc, char*** argv)
 {
-    *argc = __argc;
-    *argv = __argv;
+    if (argc)
+        *argc = __argc;
+    if (argv)
+        *argv = __argv;
 }
     
 bool Platform::hasMouse()

gameplay/src/PlatformiOS.mm

@@ -1387,8 +1387,10 @@ void Platform::getAccelerometerValues(float* pitch, float* roll)
     
 void Platform::getArguments(int* argc, char*** argv)
 {
-    argc = __argc;
-    argv = __argv;
+    if (argc)
+        *argc = __argc;
+    if (argv)
+        *argv = __argv;
 }
 
 bool Platform::hasMouse()