refs #10765/#11262 - Token: introduced cache for isMutableExpression() calls

[firewave]

No description provided.

[firewave]

This also gets rid of the Clang-only hack I introduced a while ago.

Using the code from https://trac.cppcheck.net/ticket/10765#comment:4:
Clang 21 - 2,713,071,190 -> 2,616,154,402
GCC 15 - 2,918,649,065 -> 2,718,303,437

Running it on https://github.com/firewave/mame_regtest/blob/master/mame_regtest.c :
Clang 21 - 20,959,594,045-> 20,008,068,513
GCC 15 - 22,603,210,883 -> 20,663,260,243

There is newly introduced overhead in Token::isMutableExpr() (about 2% of Ir).

[firewave]

Appears to have a massive impact on the CI.

Before:
Check time: cli/cmdlineparser.cpp: 40m 55.757s

After:
Check time: cli/cmdlineparser.cpp: 23m 17.996s

[firewave]

No differences with #7800.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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