target-supports.exp (check_effective_target_mips16_attribute): Reject hard-float modes unless the ABI is o32 or o64.

gcc/testsuite/
	* lib/target-supports.exp (check_effective_target_mips16_attribute):
	Reject hard-float modes unless the ABI is o32 or o64.
	* gcc.target/mips/inter/mips16-inter.exp: Load gcc-dg.exp instead
	of gcc.exp.  Skip the tests when mips16 code generation is not
	supported.
	* gcc.target/mips/mips16-attributes.c: Require mips16_attribute
	and use dg-add-options mips16_attribute.

From-SVN: r128723