Fix autoconf RUBY_STACK_GROW_DIRECTION on ARM devices

tool/m4/ruby_stack_grow_direction.m4

@@ -3,7 +3,7 @@ AC_DEFUN([RUBY_STACK_GROW_DIRECTION], [
     AS_VAR_PUSHDEF([stack_grow_dir], [rb_cv_stack_grow_dir_$1])
     AC_CACHE_CHECK(stack growing direction on $1, stack_grow_dir, [
 AS_CASE(["$1"],
-[m68*|x86*|x64|i?86|ppc*|sparc*|alpha*], [ $2=-1],
+[m68*|x86*|x64|i?86|ppc*|sparc*|alpha*|arm*|aarch*], [ $2=-1],
 [hppa*], [ $2=+1],
 [
   AC_RUN_IFELSE([AC_LANG_SOURCE([[