Fix assertion failure in pas_enumerator_create due to wrong alignment

https://bugs.webkit.org/show_bug.cgi?id=270993
rdar://124562475

Reviewed by Yusuke Suzuki.

In pas_enumerator_create, we assert that the payload of a pas_enumerator_region
is aligned to PAS_INTERNAL_MIN_ALIGN. This patch adds that alignment requirement
to the type definition of pas_enumerator_region so we always respect this
requirement.

* Source/bmalloc/libpas/src/libpas/pas_enumerator_region.h:

Canonical link: https://commits.webkit.org/276187@main

Source/bmalloc/libpas/src/libpas/pas_enumerator_region.h

@@ -37,7 +37,7 @@ struct pas_enumerator_region {
     pas_enumerator_region* previous;
     size_t size;
     size_t offset;
-    uint64_t payload[1];
+    PAS_ALIGNED(PAS_INTERNAL_MIN_ALIGN) uint64_t payload[1];
 };
 
 PAS_API void* pas_enumerator_region_allocate(pas_enumerator_region** region_ptr,