Remove unused ZEND_STACK_GROWS_DOWNWARDS constant

[petk]

• Check for pthread_attr_getstack defines HAVE_PTHREAD_ATTR_GETSTACK which is not used in the code.
• ZEND_STACK_GROWS_DOWNWARDS is also not used in the code.

[devnexen]

Looks good even tough I wonder where HAVE_PTHREAD_ATTR_GET_STACK comes from (typo maybe) as it does not apply for FreeBSD it is pthead_attr_getstack too. Could be fixed separately eventually.

[devnexen]

Looks good even tough I wonder where HAVE_PTHREAD_ATTR_GET_STACK comes from (typo maybe) as it does not apply for FreeBSD it is pthead_attr_getstack too. Could be fixed separately eventually.

[petk]

@devnexen, when running ./buildconf it creates main/php_config.h.in with this:

/* Define to 1 if you have the `pthread_attr_getstack' function. */
#undef HAVE_PTHREAD_ATTR_GETSTACK

then when running ./configure it runs the check for the pthread_attr_getstack. If pthreads.h is there, which probably is on some of the Linux and BSD variants, then this is added to the newly created main/php_config.h:

/* Define to 1 if you have the `pthread_attr_getstack' function. */
#define HAVE_PTHREAD_ATTR_GETSTACK 1

Perhaps it was meant for the Zend/zend_call_stack.c where pthread_get_stackaddr_np is used and guard with __APPLE__ and HAVE_PTHREAD_GET_STACKADDR_NP is added there. Yes, probably...

[petk]

I've changed this into only a single change due to usage of pthread_attr_getstack and typo constant HAVE_PTHREAD_ATTR_GET_STACK which is being resolved here then #11766

[arnaud-lb]

Thank you!