RFR: 8370077: C2: make Compile::_major_progress a boolean

[Marc Chevalier]

Simply change `Compile::_major_progress` from `int` to `bool` since we are only checking if it's non-zero.

There is one detail, we used to have

void          restore_major_progress(int progress) { _major_progress += progress; }


It is used after some verification code (maybe not only?) that may reset the major progress, using the progress saved before the said code.

It has a weird semantics:

Progress before | Progress after verification | Progress after restore
----------------|-----------------------------|-----------------------
0               | 0                           | 0
1               | 0                           | 1
0               | 1                           | 1
1               | 1                           | 2

It is rather a or than a restore, and a proper boolean version of that would be

void restore_major_progress(bool progress) { _major_progress = _major_progress || progress; }

but then, I'd argue the name is confusing. It also doesn't fit so well the idea that we just want to be back to the situation before the verification code. I suspect the unsaid assumption, is that the 3rd line (progress clear before, set by verification) is not possible. Anyway, I've tried with this or-semantics, or with a more natural

void set_major_progress(bool progress) { _major_progress = progress; }

that actually restore what we saved. Both pass (tier1-6 + some internal tests). Thus, I prefered the simpler semantics.

Thanks,
Marc

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Commit messages:
 - major_progress as bool

Changes: https://git.openjdk.org/jdk/pull/27912/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27912&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370077
  Stats: 12 lines in 2 files changed: 1 ins; 1 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/27912.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27912/head:pull/27912

PR: https://git.openjdk.org/jdk/pull/27912