Extend --check-clean (enabled on bots) to verify build commands don't include absolute paths.
The non-RBE GCC and MSVC builds still have absolute paths. GCC doesn't have -ffile-compilation-dir so it uses -fdebug-prefix-map, which is not fixable. The MSVC build has absolute path in the toolchain wrappers, which might be fixable.
TEST=ci
Change-Id: I3b984aaab7aefa7ff527f0a039ca42281224a09d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/506505
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Ryan Macnak
7d6c973ed9