* YJIT: Add `--yjit-compilation-log` flag to print out the compilation log at exit.

* YJIT: Add an option to enable the compilation log at runtime.

* YJIT: Fix a typo in the `IseqPayload` docs.

* YJIT: Add stubs for getting the YJIT compilation log in memory.

* YJIT: Add a compilation log based on a circular buffer to cap the log size.

* YJIT: Allow specifying either a file or directory name for the YJIT compilation log.

The compilation log will be populated as compilation events occur. If a directory is supplied, then a filename based on the PID will be used as the write target. If a file name is supplied instead, the log will be written to that file.

* YJIT: Add JIT compilation of C function substitutions to the compilation log.

* YJIT: Add compilation events to the circular buffer even if output is sent to a file.

Previously, the two modes were treated as being exclusive of one another. However, it could be beneficial to log all events to a file while also allowing for direct access of the last N events via `RubyVM::YJIT.compilation_log`.

* YJIT: Make timestamps the first element in the YJIT compilation log tuple.

* YJIT: Stream log to stderr if `--yjit-compilation-log` is supplied without an argument.

* YJIT: Eagerly compute compilation log messages to avoid hanging on to references that may GC.

* YJIT: Log all compiled blocks, not just the method entry points.

* YJIT: Remove all compilation events other than block compilation to slim down the log.

* YJIT: Replace circular buffer iterator with a consuming loop.

* YJIT: Support `--yjit-compilation-log=quiet` as a way to activate the in-memory log without printing it.

Co-authored-by: Randy Stauner <randy.stauner@shopify.com>

* YJIT: Promote the compilation log to being the one YJIT log.

Co-authored-by: Randy Stauner <randy.stauner@shopify.com>

* Update doc/yjit/yjit.md

* Update doc/yjit/yjit.md

---------

Co-authored-by: Randy Stauner <randy.stauner@shopify.com>
Co-authored-by: Maxime Chevalier-Boisvert <maximechevalierb@gmail.com>

```
warning: unused import: `condition::Condition`
  --> src/asm/arm64/arg/mod.rs:13:9
   |
13 | pub use condition::Condition;
   |         ^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(unused_imports)]` on by default

warning: unused import: `rb_yjit_fix_mul_fix as rb_fix_mul_fix`
   --> src/cruby.rs:188:9
    |
188 | pub use rb_yjit_fix_mul_fix as rb_fix_mul_fix;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: unused import: `rb_insn_len as raw_insn_len`
   --> src/cruby.rs:142:9
    |
142 | pub use rb_insn_len as raw_insn_len;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(unused_imports)]` on by default
```

Make asm public so it stops warning about unused public stuff in there.

This commit makes YJIT allocate memory for generated code gradually as
needed. Previously, YJIT allocates all the memory it needs on boot in
one go, leading to higher than necessary resident set size (RSS) and
time spent on boot initializing the memory with a large memset().

Users should no longer need to search for a magic number to pass to
`--yjit-exec-mem` since physical memory consumption should now more
accurately reflect the requirement of the workload.

YJIT now reserves a range of addresses on boot. This region start out
with no access permission at all so buggy attempts to jump to the region
crashes like before this change. To get this hardening at finer
granularity than the page size, we fill each page with trapping
instructions when we first allocate physical memory for the page.

Most of the time applications don't need 256 MiB of executable code, so
allocating on-demand ends up doing less total work than before. Case in
point, a simple `ruby --yjit-call-threshold=1 -eitself` takes about
half as long after this change. In terms of memory consumption, here is
a table to give a rough summary of the impact:

    | Peak RSS in MiB | -eitself example | railsbench once |
    | :-------------: | ---------------: | --------------: |
    |     before      |              265 |             377 |
    |      after      |               11 |             143 |
    |     no YJIT     |               10 |             101 |

A new module is introduced to handle allocation bookkeeping.
`CodePtr` is moved into the module since it has a close relationship
with the new `VirtualMemory` struct. This new interface has a slightly
smaller surface than before in that marking a region as writable is no
longer a public operation.