r273918 buildworld broke at semaphore

[Beeblebrox]

I posted the solution to this through the Nabble page, but there's a 
change in setting there and the messages have not gone through. So, 
re-posting to mail list:

I disabled ccache, then buildworld / buildkernel completed.

I had in /etc/make.conf:
.if ${.CURDIR:M/usr/src} || ${.CURDIR:M/usr/src/*} || 
${.CURDIR:M/asp/git/src} || ${.CURDIR:M/asp/git/src/*}
THREADS=16
#CC:=${CC:C,^cc,/usr/local/libexec/ccache/world/clang,1}
#CXX:=${CXX:C,^c\+\+,/usr/local/libexec/ccache/world/clang++,1}

The only reason I can think of is that somehow ccache was passing the 
older cached code to the buildworld process, and the reason for that 
wold be because certain clang components fail to identify themselves to 
ccache correctly.

Once I installed the newly built kernel/world and re-booted
* I deleted all under /usr/obj
* re-enabled ccache in make.conf
* re-ran "# make buildworld" > completed without problem.