VLA code: minor fix

Don't try to call get_flags() on the mob branch, where it's not defined.

x86_64-gen.c

@@ -2226,7 +2226,6 @@ ST_FUNC void gen_vla_sp_restore(int addr) {
 /* Subtract from the stack pointer, and push the resulting value onto the stack */
 ST_FUNC void gen_vla_alloc(CType *type, int align) {
     int r;
-    get_flags();
 #ifdef TCC_TARGET_PE
     /* alloca does more than just adjust %rsp on Windows */
     vpush_global_sym(&func_old_type, TOK_alloca);