Wrap Zend max execution timers check in M4 macro

- PHP_CHECK_FUNC -> AC_SEARCH_LIBS
- Redundant symbols HAVE_LIBRT and HAVE_TIMER_CREATE removed
- The rt library for some older systems (Solaris <= 10, older Linux)
  appended as needed
- This uses AC_ and AS_* macros and relies more on Autoconf shell
  code handling
- Help texts updated and synced

Author: petk

UPGRADING.INTERNALS

@@ -135,6 +135,7 @@ PHP 8.4 INTERNALS UPGRADE NOTES
    - Symbol HAVE_PDO_SQLITELIB has been removed.
    - Symbol HAVE_WAITPID has been removed.
    - Symbol HAVE_LIBPQ has been removed.
+   - Symbols HAVE_LIBRT and HAVE_TIMER_CREATE removed.
    - M4 macro PHP_DEFINE (atomic includes) removed (use AC_DEFINE and config.h).
    - M4 macro PHP_WITH_SHARED has been removed (use PHP_ARG_WITH).
    - M4 macro PHP_STRUCT_FLOCK has been removed (use AC_CHECK_TYPES).

Zend/Zend.m4

@@ -251,28 +251,7 @@ int main(void)
 AC_MSG_RESULT(done)
 
 ZEND_CHECK_SIGNALS
-
-dnl Don't enable Zend Max Execution Timers by default until PHP 8.3 to not break the ABI
-AC_ARG_ENABLE([zend-max-execution-timers],
-  [AS_HELP_STRING([--enable-zend-max-execution-timers],
-    [whether to enable zend max execution timers])],
-    [ZEND_MAX_EXECUTION_TIMERS=$enableval],
-    [ZEND_MAX_EXECUTION_TIMERS=$ZEND_ZTS])
-
-AS_CASE(["$host_alias"], [*linux*|*freebsd*], [], [ZEND_MAX_EXECUTION_TIMERS='no'])
-
-PHP_CHECK_FUNC(timer_create, rt)
-if test "$ac_cv_func_timer_create" != "yes"; then
-  ZEND_MAX_EXECUTION_TIMERS='no'
-fi
-
-if test "$ZEND_MAX_EXECUTION_TIMERS" = "yes"; then
-  AC_DEFINE(ZEND_MAX_EXECUTION_TIMERS, 1, [Use zend max execution timers])
-  CFLAGS="$CFLAGS -DZEND_MAX_EXECUTION_TIMERS"
-fi
-
-AC_MSG_CHECKING(whether to enable zend max execution timers)
-AC_MSG_RESULT($ZEND_MAX_EXECUTION_TIMERS)
+ZEND_CHECK_MAX_EXECUTION_TIMERS
 ])
 
 dnl
@@ -413,3 +392,33 @@ AS_VAR_IF([ZEND_SIGNALS], [yes],
 AC_MSG_CHECKING([whether to enable Zend signal handling])
 AC_MSG_RESULT([$ZEND_SIGNALS])
 ])
+
+dnl
+dnl ZEND_CHECK_MAX_EXECUTION_TIMERS
+dnl
+dnl Check whether to enable Zend max execution timers.
+dnl
+AC_DEFUN([ZEND_CHECK_MAX_EXECUTION_TIMERS], [dnl
+AC_ARG_ENABLE([zend-max-execution-timers],
+  [AS_HELP_STRING([--enable-zend-max-execution-timers],
+    [Enable Zend max execution timers; when building with thread safety
+    (--enable-zts), they are automatically enabled by default based on the
+    system support])],
+    [ZEND_MAX_EXECUTION_TIMERS=$enableval],
+    [ZEND_MAX_EXECUTION_TIMERS=$ZEND_ZTS])
+
+AS_CASE([$host_alias], [*linux*|*freebsd*],,
+  [ZEND_MAX_EXECUTION_TIMERS=no])
+
+AS_VAR_IF([ZEND_MAX_EXECUTION_TIMERS], [yes],
+  [AC_SEARCH_LIBS([timer_create], [rt],,
+    [ZEND_MAX_EXECUTION_TIMERS=no])])
+
+AS_VAR_IF([ZEND_MAX_EXECUTION_TIMERS], [yes],
+  [AC_DEFINE([ZEND_MAX_EXECUTION_TIMERS], [1],
+    [Define to 1 if Zend max execution timers are supported and enabled.])
+    AS_VAR_APPEND([CFLAGS], [" -DZEND_MAX_EXECUTION_TIMERS"])])
+
+AC_MSG_CHECKING([whether to enable Zend max execution timers])
+AC_MSG_RESULT([$ZEND_MAX_EXECUTION_TIMERS])
+])