Correct the path of a header file in source list. The header file path should be relative to the location of BUILD.gn. This error is detected by gn gen --check, but it hasn't because the check option has not been applied by common-mk/platform2.py. BUG=chromium:1018878 TEST=run "gn gen --check" like done by crrev.com/c/2215951 Change-Id: I3057e18739d82e2212927d6446a359f7665aac89 Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/external/modp_b64/+/2215863 Tested-by: Tatsuhisa Yamaguchi <[email protected]> Commit-Queue: Tatsuhisa Yamaguchi <[email protected]> Reviewed-by: Hidehiko Abe <[email protected]>