This set of changes clarifies the conditions for the R5900 short loop fix and extends...

This set of changes clarifies the conditions for the R5900 short loop fix and extends its test with the border cases of six and seven instructions.

	* testsuite/gas/mips/r5900.s: Extend the R5900 short loop fix
	test with border cases.
	* testsuite/gas/mips/r5900.d: Add extra expected disassembly.
	* config/tc-mips.c (can_swap_branch_p): Clarify the R5900 short
	loop hardware bug conditions.  Correct note on the R5900
	instruction count short loop fix.