Each partition's source file name was the program entry's absolute path,
and profiles name a module's local functions after it. Since programs keep
partition-local functions internal (#2449), a profile collected in one
directory missed those functions in builds from any other: a native
compiler profile collected on main named 27% of its records, holding 2.2%
of its counts, after the checkout's path. Modules now carry the entry's
file name. The partition cache key still includes the full path.
Chris Tate
23d95a99fd