[MIPS] Disable -mbranch-likely for -Os when targetting generic arch

[MIPS] Disable -mbranch-likely for -Os when targetting generic arch

gcc/
	* config/mips/mips-cpus.def: Replace PTF_AVOID_BRANCHLIKELY with
	PTF_AVOID_BRANCHLIKELY_ALWAYS for generic architecture and with
	PTF_AVOID_BRANCHLIKELY_SPEED for others.
	(mips2, mips3, mips4): Add PTF_AVOID_BRANCHLIKELY_SIZE to tune flags.
	* config/mips/mips.c (mips_option_override): Enable the branch likely
	depending on the tune flags and optimization level.
	* config/mips/mips.h (PTF_AVOID_BRANCHLIKELY): Remove.
	(PTF_AVOID_BRANCHLIKELY_SPEED): Define.
	(PTF_AVOID_BRANCHLIKELY_SIZE): Likewise.
	(PTF_AVOID_BRANCHLIKELY_ALWAYS): Likewise.

From-SVN: r240965