Mostly putting angle brackets around links to follow markdown syntax.

* YJIT: implement fast path for integer multiplication in opt_mult

* Update yjit/src/codegen.rs

Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>

* Implement mul with overflow checking on arm64

* Fix missing semicolon

* Add arm splitting for lshift, rshift, urshift

---------

Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>

* Fix 32 and 16 bit register store in YJIT

Co-Authored-By: Takashi Kokubun <takashikkbn@gmail.com>

* Remove an unnecessary diff

* Reuse an rm_num_bits result

* Use u16::MAX instead

* Update the link

Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>

* Just use sturh for 16 bits

Co-authored-by: Takashi Kokubun <takashikkbn@gmail.com>
Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>

When RUBY_DEBUG is enabled, shape ids are 16 bits.  I would like to do
16 bit comparisons, so I need to load halfwords sometimes.  This commit
adds LDURH so that I can load halfwords.

  https://developer.arm.com/documentation/ddi0596/2021-12/Base-Instructions/LDURH--Load-Register-Halfword--unscaled--?lang=en

I verified the bytes using clang:

```
$ cat asmthing.s
.global _start
.align 2

_start:
  ldurh w10, [x1]
  ldurh w10, [x1, #123]
$ as asmthing.s -o asmthing.o && objdump --disassemble asmthing.o

asmthing.o:	file format mach-o arm64

Disassembly of section __TEXT,__text:

0000000000000000 <ltmp0>:
       0: 2a 00 40 78  	ldurh	w10, [x1]
       4: 2a b0 47 78  	ldurh	w10, [x1, #123]
```

For logical instructions such as AND, there is a constraint that the N
part of the bitmask immediate must be 0. We weren't respecting this
condition previously and were silently emitting undefined instructions.

Check for this condition in the assembler and tweak the backend to
correctly detect whether a number could be encoded as an immediate in a
32 bit logical instruction. Due to the nature of the immediate encoding,
the same numeric value encodes differently depending on the size of
the register the instruction works on.

We currently don't have cases where we use 32 bit immediates but we ran
into this encoding issue during development.

* Change IncrCounter lowering on AArch64

Previously we were using LDADDAL which is not available on
Graviton 1 chips. Instead, we're going to use an exclusive
load/store group through the LDAXR/STLXR instructions.

* Update yjit/src/backend/arm64/mod.rs

Co-authored-by: Maxime Chevalier-Boisvert <maximechevalierb@gmail.com>

* YJIT: Add Opnd#sub_opnd to use only 8 bits

* Add with_num_bits and let arm64_split use it

* Add another assertion to with_num_bits

* Use only with_num_bits