Marc Chevrier authored Jul 01, 2021 and Brad King committed Jul 02, 2021

Even though Makefile generators pass source files and include
directories by absolute path to the compiler, the compiler may generate
depfile paths relative to the current working directory.  For example,
`ccache` with `CCACHE_BASEDIR` may transform paths this way.  When
reading a depfile, convert relative dependencies to absolute paths
before placing them in `compiler_depend.make`, which is later evaluated
in the top-level build directory.

Fixes: #22364