BUG #14334: vacuumdb.c build failure on openbsd

The following bug has been logged on the website:

Bug reference: 14334
Logged by: sean farrell
Email address: jungleboogie0+psql(at)gmail(dot)com
PostgreSQL version: 9.6rc1
Operating system: openbsd current
Description:

Hello,

I'm attempting to build postgresql on OpenBSD current with this config
option:
./configure --enable-cassert --enable-debug --with-perl \
--with-python --with-tcl --with-openssl --with-libxml \
--with-libxslt --with-includes=/usr/local/include

Here's part of the build where it fails:
gmake[5]: Entering directory '/home/sean/bin/postgres/src/backend'
gmake[5]: Nothing to be done for 'submake-errcodes'.
gmake[5]: Leaving directory '/home/sean/bin/postgres/src/backend'
gmake[4]: Leaving directory '/home/sean/bin/postgres/src/port'
/usr/local/bin/gmake -C ../../../src/common all
gmake[4]: Entering directory '/home/sean/bin/postgres/src/common'
/usr/local/bin/gmake -C ../backend submake-errcodes
gmake[5]: Entering directory '/home/sean/bin/postgres/src/backend'
gmake[5]: Nothing to be done for 'submake-errcodes'.
gmake[5]: Leaving directory '/home/sean/bin/postgres/src/backend'
gmake[4]: Leaving directory '/home/sean/bin/postgres/src/common'
/usr/local/bin/gmake -C ../../../src/fe_utils all
gmake[4]: Entering directory '/home/sean/bin/postgres/src/fe_utils'
gmake[4]: Nothing to be done for 'all'.
gmake[4]: Leaving directory '/home/sean/bin/postgres/src/fe_utils'
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement
-Wendif-labels -Wmissing-format-attribute -Wformat-security
-fno-strict-aliasing -fwrapv -g -O2 -I../../../src/interfaces/libpq
-I../../../src/include -I/usr/local/include/libxml2 -I/usr/local/include
-I/usr/local/include -c -o vacuumdb.o vacuumdb.c
vacuumdb.c:70: error: expected declaration specifiers or '...' before
'fd_set'
vacuumdb.c: In function 'main':
vacuumdb.c:193: error: 'FD_SETSIZE' undeclared (first use in this
function)
vacuumdb.c:193: error: (Each undeclared identifier is reported only once
vacuumdb.c:193: error: for each function it appears in.)
vacuumdb.c: In function 'GetIdleSlot':
vacuumdb.c:733: error: 'fd_set' undeclared (first use in this function)
vacuumdb.c:733: error: expected ';' before 'slotset'
vacuumdb.c:734: warning: ISO C90 forbids mixed declarations and code
vacuumdb.c:740: warning: implicit declaration of function 'FD_ZERO'
vacuumdb.c:740: error: 'slotset' undeclared (first use in this function)
vacuumdb.c:745: warning: implicit declaration of function 'FD_SET'
vacuumdb.c:759: error: too many arguments to function 'select_loop'
vacuumdb.c:775: warning: implicit declaration of function 'FD_ISSET'
vacuumdb.c: At top level:
vacuumdb.c:870: error: expected declaration specifiers or '...' before
'fd_set'
vacuumdb.c: In function 'select_loop':
vacuumdb.c:873: error: 'fd_set' undeclared (first use in this function)
vacuumdb.c:873: error: expected ';' before 'saveSet'
vacuumdb.c:898: error: 'workerset' undeclared (first use in this function)
vacuumdb.c:898: error: 'saveSet' undeclared (first use in this function)
vacuumdb.c:899: warning: implicit declaration of function 'select'
gmake[3]: *** [<builtin>: vacuumdb.o] Error 1
gmake[3]: Leaving directory '/home/sean/bin/postgres/src/bin/scripts'
gmake[2]: *** [Makefile:40: all-scripts-recurse] Error 2
gmake[2]: Leaving directory '/home/sean/bin/postgres/src/bin'
gmake[1]: *** [Makefile:35: all-bin-recurse] Error 2
gmake[1]: Leaving directory '/home/sean/bin/postgres/src'
gmake: *** [GNUmakefile:11: all-src-recurse] Error 2
*** Error 2 in /home/sean/bin/postgres (Makefile:36 'all')

Vacuumdb.c was last updated earlier last month:
https://github.com/postgres/postgres/commits/master/src/bin/scripts/vacuumdb.c

Is there something I need to do differently to get Postgresql to build?

Currently installed:
# select version();
version
----------------------------------------------------------------------------------------------
PostgreSQL 10devel on i386-unknown-openbsd6.0, compiled by gcc (GCC) 4.2.1
20070719 , 32-bit

Thanks,
Sean