Fix Makefile for OSX

Bump base SDK from 10.5 -> 10.7
Just use the builtin __APPLE__

code/sys/sys_main.c

@@ -565,7 +565,7 @@ void Sys_ParseArgs( int argc, char **argv )
 }
 
 #ifndef DEFAULT_BASEDIR
-#	ifdef MACOS_X
+#	ifdef __APPLE__
 #		define DEFAULT_BASEDIR Sys_StripAppBundle(Sys_BinaryPath())
 #	else
 #		define DEFAULT_BASEDIR Sys_BinaryPath()
@@ -646,7 +646,7 @@ int main( int argc, char **argv )
 	// Set the initial time base
 	Sys_Milliseconds( );
 
-#ifdef MACOS_X
+#ifdef __APPLE__
 	// This is passed if we are launched by double-clicking
 	if ( argc >= 2 && Q_strncmp ( argv[1], "-psn", 4 ) == 0 )
 		argc = 1;