Make einfo routines private

The libeinfo library has no consumers other than OpenRC, so there is no
reason for it to be maintained as a library. The einfo routines are now
an object that links with the rc binary.

pkgconfig/Makefile

@@ -1,6 +1,6 @@
 DIR=	${LIBDIR}/pkgconfig
-SRCS=	einfo.pc.in openrc.pc.in
-INC=	einfo.pc openrc.pc
+SRCS=	openrc.pc.in
+INC=	openrc.pc
 
 .DEFAULT:
 	${SED} -n -e 's/^VERSION=[[:space:]]*\([^[:space:]]*\).*/#define VERSION "\1${GITVER}\"/p' ../../Makefile > version.h