Fix GH-9361: Segmentation fault on script exit

Using a lot of memory may overflow some `int` calculations; to avoid
that we make sure that the operands are promoted to `size_t`.

This issue has been analyzed by @chschneider.

Closes GH-9379.

Author: cmb69

NEWS

@@ -5,6 +5,8 @@ PHP                                                                        NEWS
 - Core:
   . Fixed bug GH-9323 (Crash in ZEND_RETURN/GC/zend_call_function)
     (Tim Starling)
+  . Fixed bug GH-9361 (Segmentation fault on script exit #9379). (cmb,
+    Christian Schneider)
 
 - DOM:
   . Fixed bug #79451 (DOMDocument->replaceChild on doctype causes double free).

Zend/zend_alloc_sizes.h

@@ -19,7 +19,7 @@
 #ifndef ZEND_ALLOC_SIZES_H
 #define ZEND_ALLOC_SIZES_H
 
-#define ZEND_MM_CHUNK_SIZE (2 * 1024 * 1024)               /* 2 MB  */
+#define ZEND_MM_CHUNK_SIZE ((size_t) (2 * 1024 * 1024))    /* 2 MB  */
 #define ZEND_MM_PAGE_SIZE  (4 * 1024)                      /* 4 KB  */
 #define ZEND_MM_PAGES      (ZEND_MM_CHUNK_SIZE / ZEND_MM_PAGE_SIZE)  /* 512 */
 #define ZEND_MM_FIRST_PAGE (1)