mandoc build failures

[bch <brad.harder%gmail.com@localhost>]

#   compile  libmandoc/tag.o
--- read.o ---
/usr/src/obj/tooldir.NetBSD-7.99.34-amd64/bin/x86_64--netbsd-gcc -O2
-std=gnu99    -Wall -Wstrict-prototypes -Wmissing-prototypes
-Wpointer-arith -Wno-sign-compare  -Wno-traditional
-Wa,--fatal-warnings -Wreturn-type -Wswitch -Wshadow -Wcast-qual
-Wwrite-strings -Wextra -Wno-unused-parameter -Wno-sign-compare
-Wsign-compare -Wformat=2  -Wno-format-zero-length  -Werror   -fPIE -g
  --sysroot=/usr/src/obj/destdir.amd64 -DVERSION=\"1.13.4\"
-I/usr/src/external/bsd/mdocml/lib/libmandoc/../../dist/../include  -c
   /usr/src/external/bsd/mdocml/lib/libmandoc/../../dist/read.c -o
read.o
--- tag.o ---
/usr/src/obj/tooldir.NetBSD-7.99.34-amd64/bin/x86_64--netbsd-gcc -O2
-std=gnu99    -Wall -Wstrict-prototypes -Wmissing-prototypes
-Wpointer-arith -Wno-sign-compare  -Wno-traditional
-Wa,--fatal-warnings -Wreturn-type -Wswitch -Wshadow -Wcast-qual
-Wwrite-strings -Wextra -Wno-unused-parameter -Wno-sign-compare
-Wsign-compare -Wformat=2  -Wno-format-zero-length  -Werror   -fPIE -g
  --sysroot=/usr/src/obj/destdir.amd64 -DVERSION=\"1.13.4\"
-I/usr/src/external/bsd/mdocml/lib/libmandoc/../../dist/../include  -c
   /usr/src/external/bsd/mdocml/lib/libmandoc/../../dist/tag.c -o
tag.o
--- mdoc_validate.o ---
/usr/src/external/bsd/mdocml/lib/libmandoc/../../dist/mdoc_validate.c:
In function 'post_fo':
/usr/src/external/bsd/mdocml/lib/libmandoc/../../dist/mdoc_validate.c:816:26:
error: initialization from incompatible pointer type
[-Werror=incompatible-pointer-types]
    struct mdoc_node *p = n->last;
                          ^
/usr/src/external/bsd/mdocml/lib/libmandoc/../../dist/mdoc_validate.c:817:4:
error: implicit declaration of function 'mdoc_node_delete'
[-Werror=implicit-function-declaration]
    mdoc_node_delete(mdoc, p);
    ^
--- tag.o ---
/usr/src/external/bsd/mdocml/lib/libmandoc/../../dist/tag.c: In
function 'tag_init':
/usr/src/external/bsd/mdocml/lib/libmandoc/../../dist/tag.c:90:10:
error: implicit declaration of function 'umask'
[-Werror=implicit-function-declaration]
  omask = umask(077);
          ^
cc1: all warnings being treated as errors
*** [tag.o] Error code 1
nbmake[7]: stopped in /usr/src/external/bsd/mdocml/lib/libmandoc
--- read.o ---
/usr/src/obj/tooldir.NetBSD-7.99.34-amd64/bin/nbctfconvert -g -L
VERSION -g read.o
--- mdoc_validate.o ---
cc1: all warnings being treated as errors
*** [mdoc_validate.o] Error code 1