/usr/include errors

Attempting to build sysutils/lsof under amd64 CURRENT, I ran into the
following:

# make
===>  Building for lsof-4.77
(cd lib; make DEBUG="-O2" CFGF="-pipe -march=native
-DHASEFFNLINK=i_effnlink -DH ASF_VNODE -DHASCPUMASK_T -DHASSBSTATE
-DHAS_KVM_VNODE -DHAS_UFS1_2 -DHAS_NO_SI_U DEV -DHAS_SI_PRIV
-DHAS_SYS_SX_H -DFREEBSDV=7000 -DHASFDESCFS=2 -DHASPSEUDOFS -D
HASNULLFS -DHASIPv6 -DLSOF_VSTR=\"7.0-CURRENT\"") cc  -pipe
-march=native -DHASEFFNLINK=i_effnlink -DHASF_VNODE -DHASCPUMASK_T -DH
ASSBSTATE -DHAS_KVM_VNODE -DHAS_UFS1_2 -DHAS_NO_SI_UDEV -DHAS_SI_PRIV
-DHAS_SYS_ SX_H -DFREEBSDV=7000 -DHASFDESCFS=2 -DHASPSEUDOFS
-DHASNULLFS -DHASIPv6 -DLSOF_V STR="7.0-CURRENT" -I/usr/src/sys -O2 -c
ckkv.c In file included from /usr/src/sys/sys/mutex.h:44,
from /usr/src/sys/sys/eventhandler.h:34,
from /usr/src/sys/sys/conf.h:44, from ../dlsof.h:68,
                 from ../lsof.h:191,
                 from ckkv.c:43:
/usr/include/machine/cpufunc.h:139: error: static declaration of 'ffsl'
follows non-static declaration
/usr/include/machine/cpufunc.h:147: error: static declaration of 'fls'
follows n on-static declaration
/usr/include/strings.h:47: error: previous declaration of 'fls' was here
/usr/include/machine/cpufunc.h:155: error: static declaration of 'flsl'
follows non-static declaration
/usr/include/strings.h:48: error: previous declaration of 'flsl' was
here *** Error code 1

Stop in /usr/ports/sysutils/lsof/work/lsof_4.77/lsof_4.77_src/lib.
*** Error code 1

Stop in /usr/ports/sysutils/lsof/work/lsof_4.77/lsof_4.77_src.
*** Error code 1

Stop in /usr/ports/sysutils/lsof.

I thought perhaps I just had some stale files under include, so I
reinstalled machine/cpufunc.h and strings.h from the src tree, same
result.

Clues, anyone?

-- 
Conrad J. Sabatier <conrads_at_cox.net>