THe initial intent of the change was to only affect
`-fmacro-prefix-map=` option.
Due to the bug of `if (maps == macro_prefix_maps)` condition of initial
setting all three of:
static file_prefix_map *macro_prefix_maps; /* -fmacro-prefix-map */
static file_prefix_map *debug_prefix_maps; /* -fdebug-prefix-map */
static file_prefix_map *profile_prefix_maps; /* -fprofile-prefix-map */
matches the comparison and applied the mangling (as long as on options
were passed into those before).
As a result not only (intended) `__FILE__` embedding happened in `.data`
section, but also (unintended) debugging symbols (`-fdebug-prefix-map`)
and profiling data (`-fprofile-prefix-map`) were broken by mangling.
The patch update fixes it by explicitly passing a boolean that controls
the mangling in a single call site relevant to `-fmacro-prefix-map`.
While at it fixed `int / size_t` mismatch that caused build failure on
upcoming `gcc-14`.
Tested as:
- `nix` still has no `nlohmann_json` retention
- `gdb` can now resolve `stdc++` debugging symbols in templates
- `--coverage` has working source file paths
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