Some rather strange things are taking place while compiling devel/libedit.
I have tracked the issue down to the makelist script while it's creating ${WRKSRC}/src/fcns.h during the configure step. This has occured on amd64 of both base/head and base/stable/10 within the last couple of days. My ports tree is currently at r377334.

I guess the issue can be remedied using in-place sed during post-configure or pre-build, but I figure the scripts, makelist in particular, should be analyzed in more detail and the problem solved there.

Maybe this port really requires GNU awk, and not the awk found in base.

Manually editing ${WRKSRC}/src/fcns.h, replacing VI_]ERO with VI_ZERO solves the problem.

See below for more hints.

--- chared.lo ---
In file included from chared.c:48:
In file included from ./el.h:106:
In file included from ./chared.h:146:
./fcns.h:105:12: warning: ISO C99 requires whitespace after the macro name [-Wc99-extensions]
#define VI_]ERO                         101
           ^
--- common.lo ---
In file included from common.c:47:
In file included from ./el.h:106:
In file included from ./chared.h:146:
./fcns.h:105:12: warning: ISO C99 requires whitespace after the macro name [-Wc99-extensions]
#define VI_]ERO                         101
           ^
--- el.lo ---
In file included from el.c:59:
In file included from ./el.h:106:
In file included from ./chared.h:146:
./fcns.h:105:12: warning: ISO C99 requires whitespace after the macro name [-Wc99-extensions]
#define VI_]ERO                         101
           ^
--- emacs.lo ---
In file included from emacs.c:47:
In file included from ./el.h:106:
In file included from ./chared.h:146:
./fcns.h:105:12: warning: ISO C99 requires whitespace after the macro name [-Wc99-extensions]
#define VI_]ERO                         101
           ^
1 warning generated.
--- el.lo ---
1 warning generated.
--- common.lo ---
1 warning generated.
--- chared.lo ---
1 warning generated.
--- hist.lo ---
  CC       hist.lo
--- keymacro.lo ---
  CC       keymacro.lo
--- hist.lo ---
In file included from hist.c:48:
In file included from ./el.h:106:
In file included from ./chared.h:146:
./fcns.h:105:12: warning: ISO C99 requires whitespace after the macro name [-Wc99-extensions]
#define VI_]ERO                         101
           ^
--- map.lo ---
  CC       map.lo
--- chartype.lo ---
--- keymacro.lo ---
In file included from keymacro.c:69:
In file included from ./el.h:106:
In file included from ./chared.h:146:
./fcns.h:105:12: warning: ISO C99 requires whitespace after the macro name [-Wc99-extensions]
#define VI_]ERO                         101
           ^
--- chartype.lo ---
CC       chartype.lo
--- hist.lo ---
1 warning generated.
--- map.lo ---
In file included from map.c:48:
In file included from ./el.h:106:
In file included from ./chared.h:146:
./fcns.h:105:12: warning: ISO C99 requires whitespace after the macro name [-Wc99-extensions]
#define VI_]ERO                         101
           ^
map.c:676:12: error: use of undeclared identifier 'VI_ZERO'
        /*  48 */       VI_ZERO,                /* 0 */
                        ^
1 warning and 1 error generated.
*** [map.lo] Error code 1

make[4]: stopped in /usr/ports/workdirs/usr/ports/devel/libedit/work/libedit-20141029-3.1/src
--- chartype.lo ---
In file included from chartype.c:43:
In file included from ./el.h:106:
In file included from ./chared.h:146:
./fcns.h:105:12: warning: ISO C99 requires whitespace after the macro name [-Wc99-extensions]
#define VI_]ERO                         101
           ^
--- keymacro.lo ---
1 warning generated.
--- chartype.lo ---
1 warning generated.
1 error

make[4]: stopped in /usr/ports/workdirs/usr/ports/devel/libedit/work/libedit-20141029-3.1/src
*** [all] Error code 2

make[3]: stopped in /usr/ports/workdirs/usr/ports/devel/libedit/work/libedit-20141029-3.1/src
1 error

make[3]: stopped in /usr/ports/workdirs/usr/ports/devel/libedit/work/libedit-20141029-3.1/src
*** [all-recursive] Error code 1

make[2]: stopped in /usr/ports/workdirs/usr/ports/devel/libedit/work/libedit-20141029-3.1
1 error

make[2]: stopped in /usr/ports/workdirs/usr/ports/devel/libedit/work/libedit-20141029-3.1
*** [all] Error code 2

make[1]: stopped in /usr/ports/workdirs/usr/ports/devel/libedit/work/libedit-20141029-3.1
1 error

make[1]: stopped in /usr/ports/workdirs/usr/ports/devel/libedit/work/libedit-20141029-3.1
===> Compilation failed unexpectedly.
Try to set MAKE_JOBS_UNSAFE=yes and rebuild before reporting the failure to
the maintainer.
*** Error code 1

Stop.
make: stopped in /usr/ports/devel/libedit