Increase zend.reserved_stack_size minimum value in ASAN/MSAN builds

[arnaud-lb]

zend.reserved_stack_size is the size of the stack space that is reserved for native code called by the VM. This reserved space is similar to the shadow space described in https://pangin.pro/posts/stack-overflow-handling.

The minimum and default value of zend.reserved_stack_size is ZEND_ALLOCA_MAX_SIZE + some empirically chosen value. If this is too low, the program may crash as if no stack limit was in place.

ASAN/MSAN builds use considerably more stack space due to instrumentation, so this default value is too low in these builds. https://clang.llvm.org/docs/AddressSanitizer.html#limitations mentions an increase of up to 3x, but the stack usage of individual functions can increase much more than that. For example, here is a stack trace annotated with stack usage of each function as reported by -fstack-usage:

 non-asan asan
total 5176 52912
zend_mm_small_size_to_bin 40 88
zend_mm_alloc_heap 96 424
_zend_mm_alloc 64 120
zend_mm_realloc_heap 192 1224
_erealloc 96 184
_safe_erealloc 64 152
zend_stack_push 48 296
enter_nesting 48 152
lex_scan 1056 30424
zendlex 80 152
zendparse 2448 17688
zend_compile 224 280
compile_file 304 184
compile_filename 144 216
zend_include_or_eval 176 408
ZEND_INCLUDE_OR_EVAL_SPEC_CONST_HANDLER 96 920
execute_ex <-- stack limit check is made here

In this PR I increase the minimum and default value of zend.reserved_stack_size by 10x in ASAN/MSAN builds.

[iluuu1994]

Unfortunately, this doesn't seem to resolve the issue for me locally. I still get stack-overflow errors for most tests. stack_limit_005.phpt gives me "Uncaught Error: Call to a member function f() on null", and stack_limit_013.phpt no output at all. I'm on gcc version 13.1.1.

[arnaud-lb]

I will close this PR then, as the stack usage is too unpredictable under instrumentation. Since my initial goal was to avoid stack overflows while fuzzing, it might be preferable to just set zend.reserved_stack_size to an arbitrarily large value in the fuzzer's hardcoded ini settings.