Fix optional intermediates path for unbundled builds

On an unbundled build, if an include directory was missing, I generated
an intermediate path with PathForModuleOut. That included another copy
of $OUT_DIR, which I didn't notice. This fails if $OUT_DIR is an
absolute directory. Just manually set up the path for now.

Change-Id: I3821d562c929e69ed2fccb7e88affed384a7789e
1 file changed