Previously, including `BLI_strict_flags.h` caused compile errors for all
shadowed values. Generally, this is fine, but sometimes it may catch more cases
than desirable. For example, adding `int U;` in `init_data` in
`MOD_correctivesmooth.cc` causes an error because there is the global `U` symbol
(user prefs).
While not an issue right now, this can cause unexpected compile errors when
adding additional includes. I ran into this while working on a tool that adds
additional includes automatically as part of its operation.
Fortunately, GCC supports a slightly weaker variant of this error:
`-Wshadow=local`. This only covers the case we mainly care about where local
variables are shadowed by other local variables.
Pull Request: https://projects.blender.org/blender/blender/pulls/136389
06ddccac05