Initial libs such as csu are always built (.PHONY), and their
installation to WORLDTMP was causing all the subsequent libraries to
be considered out-of-date even when in reality they were not. Use
install -C more consistently everywhere to avoid unnecessarily
updating the mtimes in WORLDTMP, fixing this problem.
This cut down my no-change buildworld time from 30 to 15 seconds.
Fixes: https://lists.freebsd.org/pipermail/freebsd-current/2016-May/061481.html
TODO.1
Reviewed by: sjg
Sponsored by: https://www.patreon.com/valpackett
Differential Revision: https://reviews.freebsd.org/D39980
da6620e495