Method#unbind clones the method entry, preserving its defined_class.
For methods mixed in via include/extend, defined_class is an ICLASS,
causing UnboundMethod#== to return false when comparing against the
same method obtained via Module#instance_method.

Resolve ICLASS defined_class in method_eq.

[Bug #21873]

When a CC is invalidated only the klass field is set to 0. After it's
invalidated it isn't safe to access the CME, as it may have been freed.

I made a similar change in Ruby 4.0 in
640a2f1dc77c0ecf226dbd71cf7a1eb876a1f037, but assumed it was due to the
changes we'd made to callcaches making klass a weak-reference.

Co-authored-by: Christian Bruckmayer <christian.bruckmayer@shopify.com>

[Bug #21860]

If a thread was holding this lock before fork, it will not exist in the
child process. We should re-initialize these locks as we do with the VM
locks when forking.

Co-Authored-By: John Hawthorn <john@hawthorn.email>
Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>

[Bug #21931]

Keep tmp alive while RARRAY_CONST_PTR(tmp) is used by rb_str_format.

[alan: sunk the guard below usage]
Reviewed-by: Alan Wu <XrXr@users.noreply.github.com>

	[PATCH] Don't force major GC when there are allocatable slots

	[Bug #21838]

	When we have allocatable slots, we can grow the heap instead of forcing
	a major GC. This prevents major GC to be ran very often in certain situations.
	See the ticket for more details.

	On ruby-bench, we can see that this patch doesn't cause any significant
	regressions:

	    --------------  -----------  ----------  ---------  -----------  ----------  ---------  --------------  -------------
	    bench           master (ms)  stddev (%)  RSS (MiB)  branch (ms)  stddev (%)  RSS (MiB)  branch 1st itr  master/branch
	    activerecord    148.2        0.3         59.2       150.0        0.8         69.7       1.015           0.988
	    chunky-png      435.2        0.3         72.9       438.8        0.1         66.7       0.993           0.992
	    erubi-rails     733.8        1.2         118.7      704.8        0.2         98.3       1.077           1.041
	    hexapdf         1400.4       1.1         247.0      1405.0       0.9         223.7      0.986           0.997
	    liquid-c        32.5         3.3         32.8       32.5         2.1         30.7       1.042           0.999
	    liquid-compile  31.0         1.7         35.1       33.4         3.9         32.8       0.938           0.928
	    liquid-render   84.7         0.4         30.8       86.3         0.4         30.8       0.981           0.982
	    lobsters        594.7        0.6         310.5      596.6        0.4         306.0      1.057           0.997
	    mail            75.6         2.8         53.3       76.9         0.7         53.2       0.968           0.982
	    psych-load      1122.8       1.2         29.2       1145.1       0.4         31.7       0.964           0.981
	    railsbench      1244.7       0.3         115.5      1254.8       1.1         115.2      0.939           0.992
	    rubocop         103.7        0.5         94.1       104.3        0.5         92.4       0.985           0.994
	    ruby-lsp        88.3         0.6         78.5       88.5         1.2         77.9       0.992           0.997
	    sequel          26.9         0.9         33.6       28.3         1.4         32.1       0.954           0.952
	    shipit          1119.3       1.5         171.4      1075.7       2.1         162.5      1.873           1.040
	    --------------  -----------  ----------  ---------  -----------  ----------  ---------  --------------  -------------

Example insns diff for `def x = [3]; def a(...) = b(*x, 2, 3, ...)`

     == disasm: #<ISeq:a@-e:1 (1,13)-(1,42)>
     local table (size: 1, argc: 0 [opts: 0, rest: -1, post: 0, block: -1, kw: -1@-1, kwrest: -1])
     [ 1] "..."@0
     0000 putself                                                          (   1)[Ca]
     0000 putself
     0000 opt_send_without_block                 <calldata!mid:x, argc:0, FCALL|VCALL|ARGS_SIMPLE>
     0000 splatarray                             true
     0000 putobject                              2
     0000 putobject                              3
    +0000 pushtoarray                            2
     0000 getlocal_WC_0                          "..."@0
     0000 sendforward                            <calldata!mid:b, argc:1, ARGS_SPLAT|ARGS_SPLAT_MUT|FCALL|FORWARDING>, nil
     0000 leave                                  [Re]

This matches the insns produced by parse.y

	[PATCH] fix underflow