Remove HEAP_ALIGN_LOG setting in configure.ac for OpenBSD/MirOS

The ruby setting was renamed to HEAP_PAGE_ALIGN_LOG, but the
configure.in (now configure.ac) file was not updated, so the
setting had no effect.  The configure setting is unnecessary
after OpenBSD 5.2 and MirOS has been discontinued (with the last
release being over 10 years ago), so it is better to just remove
the related configure setting.

Fix [Bug #13438]
From: Jeremy Evans <code@jeremyevans.net>



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66086 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

configure.ac

@@ -1641,34 +1641,6 @@ AS_IF([test $rb_cv_stack_end_address != no], [
   AC_DEFINE_UNQUOTED(STACK_END_ADDRESS, $rb_cv_stack_end_address)
 ])
 
-# posix_memalign(memptr, alignment, size) implemented for OpenBSD 4.8 doesn't work if alignment > MALLOC_PAGESIZE.
-# [ruby-core:42158] https://bugs.ruby-lang.org/issues/5901
-# OpenBSD 5.2 fixed the problem. (src/lib/libc/stdlib/malloc.c:1.142)
-# MirOS #10semel has the problem but fixed in the repository.  (src/lib/libc/stdlib/malloc.c:1.9)
-AS_CASE(["$target_os"],
-[openbsd*|mirbsd*], [
-  AC_CACHE_CHECK(for heap align log on openbsd, rb_cv_page_size_log,
-    [rb_cv_page_size_log=no
-     for page_log in 12 13; do
-       AC_TRY_RUN([
-#include <math.h>
-#include <unistd.h>
-
-int
-main() {
-  if ((int)log2((double)sysconf(_SC_PAGESIZE)) != $page_log) return 1;
-  return 0;
-}
-       ],
-       rb_cv_page_size_log="$page_log"; break)
-     done])
-  AS_IF([test $rb_cv_page_size_log != no], [
-    AC_DEFINE_UNQUOTED(HEAP_ALIGN_LOG, $rb_cv_page_size_log)
-  ], [
-    AC_DEFINE_UNQUOTED(HEAP_ALIGN_LOG, 12)
-  ])
-])
-
 dnl Checks for library functions.
 AC_TYPE_GETGROUPS
 AC_TYPE_SIGNAL

gc.c

@@ -649,10 +649,8 @@ typedef struct rb_objspace {
 } rb_objspace_t;
 
 
-#ifndef HEAP_PAGE_ALIGN_LOG
 /* default tiny heap size: 16KB */
 #define HEAP_PAGE_ALIGN_LOG 14
-#endif
 #define CEILDIV(i, mod) (((i) + (mod) - 1)/(mod))
 enum {
     HEAP_PAGE_ALIGN = (1UL << HEAP_PAGE_ALIGN_LOG),