winegcc: Forward -mcpu to winebuild.

tools/winegcc/winegcc.c

@@ -1391,6 +1391,8 @@ int main(int argc, char **argv)
                         opts.force_pointer_size = 8;
 			raw_linker_arg = 1;
                     }
+                    else if (strncmp("-mcpu=", argv[i], 6) == 0)
+                        strarray_add(opts.winebuild_args, argv[i]);
 		    break;
                 case 'n':
                     if (strcmp("-nostdinc", argv[i]) == 0)