Testsuite: Remove all Wstrict-overflow tests.
All remaining tests specifically checking for `-Wstrict-overflow` behavior have been removed.
The testsuite no longer contains any tests that explicitly check for -Wstrict-overflow warnings. Since these warnings are no longer issued, the tests were either compile tests that were not expected to issue a warning, or XFAIL tests. Removing them simplifies the testsuite and avoids confusion.
In Details
This commit removes a large number of test files from the GCC testsuite, all named gcc.dg/Wstrict-overflow-*.c. Search terms: GCC testsuite -Wstrict-overflow
For Context
A compiler testsuite ensures the compiler produces correct code and diagnostics. As features are deprecated or removed from the compiler, corresponding tests are removed, which keeps the testsuite maintainable and focused on current functionality. This commit removes the tests for the deprecated -Wstrict-overflow flag.