No, I am not running current. This is a stock installation of 4.6 and
the source is from the src.tar.gz file from the same place.
I went ahead and wiped the entire src tree and started from scratch.
The compile started working but then died later:
In file included from ../../../../kern/init_sysent.c:14:
../../../../sys/syscallargs.h:1119: Internal compiler error in
'grokdeclarator', at c-decl.c:4505
No idea what happened there.