The frontend supports this via new options -index-unit-output-path and
-index-unit-output-path-filelist that mirror -o and -output-filelist. These are
intended to allow sharing index data across builds in separate directories (so
different -o values) that are otherwise equivalent as far as the index data is
concerned (e.g. an ASAN build and a non-ASAN build) by supplying the same
-index-unit-output-path for both.
This change updates the driver to add these new options to the frontend
invocation 1) when a new "index-unit-output-path" entry is specified for one
or more input files in the -output-file-map json or 2) if -index-file is
specified, when a new -index-unit-output-path driver option is passed.
Resolves rdar://problem/74816412
These new options mirror -o and -output-filelist and are used instead
of those options to supply the output file path(s) to record in the
index store. This is intended to allow sharing index data across
builds in separate directories that are otherwise equivalent as far
as the index data is concered (e.g. an ASAN build and a non-ASAN build)
by supplying the same -index-unit-output-path for both.
Resolves rdar://problem/74816412
