Update for autoconf 2.70

	---
	 configure.ac                         | 232 +++++++++++++++++------------------
	 tool/m4/ruby_check_builtin_setjmp.m4 |   8 +-
	 tool/m4/ruby_check_printf_prefix.m4  |   9 +-
	 tool/m4/ruby_check_setjmp.m4         |   6 +-
	 tool/m4/ruby_check_sysconf.m4        |   6 +-
	 tool/m4/ruby_cppoutfile.m4           |   4 +-
	 tool/m4/ruby_decl_attribute.m4       |   4 +-
	 tool/m4/ruby_dtrace_available.m4     |   2 +-
	 tool/m4/ruby_dtrace_postprocess.m4   |   2 +-
	 tool/m4/ruby_mingw32.m4              |   4 +-
	 tool/m4/ruby_stack_grow_direction.m4 |   4 +-
	 tool/m4/ruby_try_cflags.m4           |   2 +-
	 tool/m4/ruby_try_cxxflags.m4         |   2 +-
	 tool/m4/ruby_try_ldflags.m4          |   2 +-
	 14 files changed, 143 insertions(+), 144 deletions(-)

	Revert AC_PROG_CC_C99 for -std=gnu99 option to gcc 4.8

	---
	 configure.ac | 5 ++++-
	 1 file changed, 4 insertions(+), 1 deletion(-)