Copy symlink farm creation tool from Bazel.

SymlinkTree is one of the action types Blaze returns in response to
`aquery` (action query). build-runfiles is a tool copied from Bazel
to implement this action (see src/main/tools/build-runfiles.cc in
the Bazel Git repo). It creates a symlink farm (i.e., a directory
hiearchy consisting of symlinks) from a given manifest. Mixed builds
need this tool the mixed builds (in particular, every Python applicaion
has a runtime symlink farm).

Bug: 232085015
Test: m USE_BAZEL_ANALYSIS=1 com.android.adbd
Change-Id: I9cfcb33cb7d0f63bd36ffd2b4101f53cfc6a42fc