Increase SEG_ALLOC_SIZE_MAX to 64MB to support OPcache JIT on Solaris

The SysV shared memory allocator in OPcache hardcodes a maximum segment
size of 32MB (SEG_ALLOC_SIZE_MAX). With JIT enabled, OPcache reserves
64MB (ZEND_JIT_DEFAULT_BUFFER_SIZE) from the last segment, causing
startup to fail with "Insufficient shared memory!".

This patch increases SEG_ALLOC_SIZE_MAX to 64MB so the reserved JIT buffer
fits in a single segment. Behavior on other platforms using mmap remains
unaffected.

Fixes #20718.

Author: psumbera

ext/opcache/shared_alloc_shm.c

@@ -42,7 +42,7 @@
 # define MIN(x, y) ((x) > (y)? (y) : (x))
 #endif
 
-#define SEG_ALLOC_SIZE_MAX 32*1024*1024
+#define SEG_ALLOC_SIZE_MAX 64*1024*1024 /* 64MB to match ZEND_JIT_DEFAULT_BUFFER_SIZE */
 #define SEG_ALLOC_SIZE_MIN 2*1024*1024
 
 typedef struct  {