K 10
svn:author
V 8
bdrewery
K 8
svn:date
V 27
2018-06-27T16:58:10.987388Z
K 7
svn:log
V 392
tinderbox: Only build clang/lld once if needed.

Need to handle LLD_BOOTSTRAP separately (for archs like i386).
This would be much better off with an off-by-default option like
SHARED_TOOLCHAIN that universe force-enabled.  Then a normal buildworld
would store the toolchain there if enabled and otherwise in WORLDTMP
with only the 1 arch selected.

MFC after:	3 weeks
Sponsored by:	Dell EMC

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