* src/vm/jit/code.c (code_get_stack_frame_size): Implement stack alignment

* src/vm/jit/code.c (code_get_stack_frame_size): Implement stack alignment
for MIPS.

* src/vm/jit/mips/md.c (md_patch_replacement_point): Added.

* src/vm/jit/mips/codegen.c (codegen): Handle replacement points.
8-byte align blocks that start with replacement points.

* src/vm/jit/mips/asmpart.S (asm_replacement_out): Added.
(asm_replacement_in): Likewise.

* src/vm/jit/replace.c (replace_activate_replacement_point): Activated
for MIPS.
(replace_deactivate_replacement_poin): Likewise.
(replace_me): Likewise.
(replace_read_executionstate): MIPS also keeps returnAddress in ITMP1.
(replace_write_executionstate): Likewise.

* doc/stack_frames.txt: Documented MIPS stack frames.

* src/vm/jit/powerpc/asmpart.S (asm_replacement_out): Fixed comment.