Several ports to enable r6 compact branch optimizations on MIPS64

Port 3573d3cb

Original commit message:
MIPS: r6 compact branch optimization.

Port bddf8c9e

Original commit message:
MIPS: Fix trampoline pool handling in MacroAssembler::BranchShort()

Port 6993cd0d

Original commit message:
MIPS: Fix 'MIPS:r6 compact branch optimization.'

Jic and jialc compact branch ops are fixed as they does
not have 'forbidden slot' restriction. Also COP1 branches
(CTI instructions) added to IsForbiddenAfterBranchInstr().

Port bb332195

Original commit message:
MIPS: Fix trampoline pool handling in MacroAssembler::BranchShort()

Port c91bcf71

Original commit message:
MIPS: Fix trampoline pool handling in MacroAssembler::BranchShort()
for r6.

BUG=

Review URL: https://codereview.chromium.org/1534183002

Cr-Commit-Position: refs/heads/master@{#33136}