libudev: include use_tools missing

Libtool and pkg-config. Should've read introspection.m4 besides
configure.ac. But patch the latter to ok gperf absence, libudev
builds without, wip/udev daemon needs it.

libudev/Makefile

@@ -4,6 +4,7 @@ COMMENT=	Device enumeration and database of constants
 CONFIGURE_ARGS+=	--disable-programs
 
 pre-configure:
+	sed -i 's/ERROR\(.*gperf\)/WARN\1/' ${WRKSRC}/configure.ac
 	cd ${WRKSRC} &&autoreconf -fiv
 
 .include "../../wip/libudev/Makefile.common"

libudev/Makefile.common

@@ -14,7 +14,8 @@ HOMEPAGE=	https://wiki.gentoo.org/wiki/Project:Eudev
 LICENSE=	gnu-gpl-v2
 
 ONLY_FOR_PLATFORM=	Linux-*-*
-USE_TOOLS+=	autoconf automake gmake
+USE_TOOLS+=	autoconf automake gmake pkg-config
+USE_LIBTOOL=	yes
 GNU_CONFIGURE=	yes
 CONFIGURE_ARGS+=	--with-rootrundir=${VARBASE}/run
 

udev/Makefile

@@ -12,5 +12,6 @@ pre-configure:
 	sed -i 's,/run,"UDEV_ROOT_RUN",' ${WRKSRC}/src/udev/*.c
 	cd ${WRKSRC} &&autoreconf -fiv
 
+.include "../../devel/gperf/buildlink3.mk"
 .include "../../wip/libudev/buildlink3.mk"
 .include "../../wip/libudev/Makefile.common"