MIPS: Fix 'Assembler support for internal references.'

MIPS: Fix 'Assembler support for internal references.'

Added new INTERNAL_REFERENCE_ENCODED RelocInfo type to differentiate MIPS existing use of internal references in instructions from the new raw pointer reference needed for dd(Label*).

BUG=
TEST=cctest/test-assembler-mips/jump_tables1, cctest/test-assembler-mips/jump_tables2, cctest/test-assembler-mips/jump_tables3, cctest/test-run-machops/RunSwitch1

Review URL: https://codereview.chromium.org/922043005

Cr-Commit-Position: refs/heads/master@{#26651}