[heap] Fix GCC build because of undefined CHAR_BIT

Explicitly #include climits header for CHAR_BIT.

Bug: v8:12691
Change-Id: I9d7a28543883a5387e006c4b6ee4491243a06207
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3516925
Auto-Submit: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79446}

src/heap/base/active-system-pages.cc

@@ -4,6 +4,8 @@
 
 #include "src/heap/base/active-system-pages.h"
 
+#include <climits>
+
 #include "src/base/bits.h"
 #include "src/base/macros.h"