Update build-tools to ab/3725807

Besides the compiler/libc++ update that caused everything to change, the
major update here is to ninja. Faster startup times due to less
reloading, and the ability to use the depslog when writing multiple
output files.

Bug: 32749731
Test: m -j
Change-Id: I84cac9aac12d24f70b0dd163d67cb71a1b31c09b