mips.c (override_options): Use mips_costs to derive the default branch cost.

mips.c (override_options): Use mips_costs to derive the default branch cost.

gcc/
	* config/mips/mips.c (override_options): Use mips_costs to derive
	the default branch cost.
	* config/mips/mips.h (BRANCH_COST): Use mips_branch_cost rather
	than mips_costs.
	* config/mips/mips.opt (mbranch-cost=): New option.
	* doc/invoke.texi (-mbrach-cost): Document new MIPS option.

gcc/testsuite/
	* gcc.target/mips/branch-cost-1.c: New test.
	* gcc.target/mips/branch-cost-2.c: Likewise.

From-SVN: r126846