When running a build with the following:

$ gradle -PBUILD_TOOLS_DOWNLOAD_SCRIPT=/mybuildtoolsdir/build-tools.gradle -PCOMPILE_MEDIA=true

All of the components use the pkg-config from the "${toolchainDir}" directory except media, which runs it from /usr/bin (or wherever it is in your PATH).

We discovered this while running a test build on a new Linux machine that was missing a couple of packages needed to build media. The build should have found the needed packages from "${toolchainDir}" but instead failed with an error.