Fix issue where linux_bionic cannot find build number

For some reason linux_bionic builds don't seem to be able to find the
build-number unless we've lunched to something. Do that and fix up for
the new location of the build-number.txt file.

Bug: 151059142
Test: DIST_DIR=$PWD/out/dist ./art/tools/dist_linux_bionic.sh -j80 com.android.art.host com.android.support.apexer
Change-Id: If2ad57f4301d723b2a53f741643826682d5863b0
1 file changed