Allow the alignas test to run on 32-bit profiles. (#642)

Co-authored-by: Virgil Serbanuta <virgil.serbanuta>

Author: virgil-serbanuta

tests/unit-fail-compilation/alignas.c

@@ -1,7 +1,7 @@
 #include <stdalign.h>
 
 struct {
-      alignas(int) long long int x;
+      alignas(short) long long int x;
 };
 
 int main(void) {