===> usr.sbin/pppd/pppd
[...]
cc -O -I. -DHAVE_PATHS_H -I/usr/src/usr.sbin/pppd/pppd/../../../lib/libpcap
-DPPP_FILTER -DCBCP_SUPPORT  -Werror -Wall -Wstrict-prototypes
-Wmissing-prototypes -Wpointer-arith  -c sys-bsd.c
sys-bsd.c:29: syntax error before string constant
cc1: warnings being treated as errors
sys-bsd.c:29: warning: function declaration isn't a prototype
sys-bsd.c:29: warning: data definition has no type or storage class
*** Error code 1

Stop.