sysutils/slurm-wlm: Unbreak build: add perl5 to the build environment

It's not clear to me how this ever built given all the places in
configure that use the "perl" command. But it was building (for me
at least) as recently as yesterday. I can only assume something
changed in the ports build infrastructure.

Anyway, this lets me build kicad again.

sysutils/slurm-wlm/Makefile

@@ -20,8 +20,9 @@ LIB_DEPENDS=	libjson-c.so:devel/json-c \
 		libmunge.so:security/munge \
 		liblz4.so:archivers/liblz4
 
-USES=		compiler:c11 cpe gmake gnome libtool localbase lua pkgconfig \
-		python:build readline shebangfix ssl tar:bz2
+USES=		compiler:c11 cpe gmake gnome libtool localbase lua perl5 \
+		pkgconfig python:build readline shebangfix ssl tar:bz2
+USE_PERL5=	build
 CPE_VENDOR=	schedmd
 USE_LDCONFIG=	yes
 USE_RC_SUBR=	slurmctld slurmd