Revert^2 "Remove (host) x86_64-linux gcc-4.8 bins"

This reverts commit 3784b29f131c970febc6ccfe3117b0880915477c and
relands commit bb0d30b291585c0ad56611ca85ef1e9156bd28b9.

Reason for revert: the "platform usage" alluded to in aosp/1887822
was fixed in aosp/1888176. Additional usage by external/qemu was
fixed in aosp/1901256 and aosp/1909473.

Bug: 203698882
Bug: 206466604
Change-Id: I1d55a786c4ec7706edf8d32ba1866214896651f4
34 files changed