Ensure softfloat and singlefloat take precedence in consistency checks

gas/

	* tc-mips.c (check_fpabi): Move softfloat and singlefloat
	checks higher.

gas/testsuite/

	* gas/mips/attr-gnu-4-5-msingle-float.l: New file.
	* gas/mips/attr-gnu-4-5-msingle-float.s: Likewise.
	* gas/mips/attr-gnu-4-5-msoft-float.l: Likewise.
	* gas/mips/attr-gnu-4-5-msoft-float.s: Likewise.
	* gas/mips/attr-gnu-4-6-msingle-float.l: Update expected output.
	* gas/mips/attr-gnu-4-6-msoft-float.l: Likewise.
	* gas/mips/attr-gnu-4-7-msingle-float.l: Likewise.
	* gas/mips/attr-gnu-4-7-msoft-float.l: Likewise.
	* gas/mips/mips.exp: Update expected output for FP ABI 5,6,7.