toolchain/51118: libctf tools build fails on FreeBSD 10.3-RELEASE

[jmcneill%invisible.ca@localhost]

>Number:         51118
>Category:       toolchain
>Synopsis:       libctf tools build fails on FreeBSD 10.3-RELEASE
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri May 06 11:00:00 +0000 2016
>Originator:     Jared McNeill
>Release:        HEAD
>Organization:
>Environment:
FreeBSD undine.invisible.ca 10.3-RELEASE FreeBSD 10.3-RELEASE #0 r297264: Fri Mar 25 02:10:02 UTC 2016     root%releng1.nyi.freebsd.org@localhost:/usr/obj/usr/src/sys/GENERIC  amd64

>Description:
Attempting to build tools fails in compat_defs.h while building libctf:

/usr/home/jmcneill/netbsd/src/tools/libctf/../compat/compat_defs.h:665:2: error: "Don't know how to define SCN[diouxX]8"
#error "Don't know how to define SCN[diouxX]8"
 ^
...

This error happens when UCHAR_MAX is not defined. The failed command was:

cc -O  -DCTF_OLD_VERSIONS -I/usr/home/jmcneill/netbsd/src/tools/libctf/../compat  -I/usr/home/jmcneill/netbsd/src/tools/libctf/../../external/cddl/osnet/sys  -I/usr/home/jmcneill/netbsd/src/tools/libctf/../../external/cddl/osnet/include  -I/usr/home/jmcneill/netbsd/src/tools/libctf/../../external/cddl/osnet/dist/head  -I/usr/home/jmcneill/netbsd/src/tools/libctf/../../external/cddl/osnet/dist/common/ctf  -I/usr/home/jmcneill/netbsd/src/tools/libctf/../../external/cddl/osnet/dist/lib/libctf/common  -I/usr/home/jmcneill/netbsd/src/tools/libctf/../../external/cddl/osnet/dist/uts/common  -I/usr/home/jmcneill/netbsd/src/tools/libctf/../../external/bsd/elftoolchain/dist/libelf -DHAVE_NBTOOL_CONFIG_H=1 -D_FILE_OFFSET_BITS=64  -I/usr/home/jmcneill/netbsd/src/obj/tooldir.FreeBSD-10.3-RELEASE-amd64/include/compat -I/usr/home/jmcneill/netbsd/src/tools/compat  -DHAVE_NBTOOL_CONFIG_H=1 -D_FILE_OFFSET_BITS=64 -I/usr/home/jmcneill/netbsd/src/obj/tooldir.FreeBSD-10.3-RELEASE-amd64/include -I/usr/hom
 e/jmcneill/netbsd/src/obj/tooldir.FreeBSD-10.3-RELEASE-amd64/include/nbinclude -c -o ctf_hash.lo.o    /usr/home/jmcneill/netbsd/src/tools/libctf/../../external/cddl/osnet/dist/common/ctf/ctf_hash.c

Adding -H to this shows what's going on:

... /usr/include/limits.h
.... /usr/home/jmcneill/netbsd/src/tools/libctf/../../external/cddl/osnet/sys/sys/limits.h

UCHAR_MAX is defined in the native sys/limits.h here, and compat_defs.h with external/cddl/osnet/sys in the search path doesn't hvae a chance to pick it up.
>How-To-Repeat:
On FreeBSD 10.3-RELEASE:

./build.sh -U -m amd64 -j4 tools
>Fix: