Cocoa: Silence type warning

Add const for "qemu" character literal, to avoid:

warning: initialization discards qualifiers from pointer target type

An earlier patch by John proposed to use char[5]. Since we do not modify
the text and later copy it into malloc'ed memory, marking it as const
seems sufficient.
Signed-off-by: NAndreas Färber <andreas.faerber@web.de>
Cc: John Arbuckle <programmingkidx@gmail.com>
Signed-off-by: Nmalc <av1474@comtv.ru>

cocoa.m

@@ -791,7 +791,7 @@ static int cocoa_keycode_to_qemu(int keycode)
     if(returnCode == NSCancelButton) {
         exit(0);
     } else if(returnCode == NSOKButton) {
-        char *bin = "qemu";
+        const char *bin = "qemu";
         char *img = (char*)[ [ sheet filename ] cStringUsingEncoding:NSASCIIStringEncoding];
 
         char **argv = (char**)malloc( sizeof(char*)*3 );