Fix regressions in legacy implicit include directories

Follow up !2716 (merged) with a few fixes:

• The legacy exclusion of /usr/include should apply only to C, CXX, and CUDA, but not to Fortran.

• The Platform/Darwin module needs to add <sdk>/usr/include to the initial default implicit include directories rather than unconditionally appending it. Platform/UnixPaths had a similar change for plain /usr/include in the original MR.

• The detected value of CMAKE_<LANG>_IMPLICIT_INCLUDE_DIRECTORIES has paths that already include the sysroot prefix when using CMAKE_SYSROOT, so do not add another copy of the sysroot prefix on such paths.

Fixes: #18914 (closed)

changed milestone to %3.14.0

Warnings:

• Eligible for the 3.14.x branch.

The warnings do not need to be fixed, but it is recommended to do so.

mentioned in merge request !2716 (merged)

added workflow:nightly-testing label

Cc: @chuck

added 1 commit

• 6fc33829 - Update logic for sysroot in detected implicit include directories

Compare with previous version

Do: stage

Warnings:

• Eligible for the 3.14.x branch.

The warnings do not need to be fixed, but it is recommended to do so.

mentioned in issue #18914 (closed)

Do: merge

removed workflow:nightly-testing label

mentioned in commit 50ba2f01

merged

mentioned in commit 30783add

mentioned in merge request !2945 (merged)

mentioned in issue #18936 (closed)

mentioned in merge request !2981 (merged)

mentioned in merge request !3159 (merged)

mentioned in merge request !4315 (merged)