Add pkg-config file for libarchive

Requested by:	bapt
MFC after:	1 week

lib/libarchive/Makefile

@@ -49,6 +49,12 @@ CFLAGS+=	-DPPMD_32BIT
 .endif
 NO_WCAST_ALIGN.clang=
 
+.ifndef COMPAT_32BIT
+beforeinstall:
+	${INSTALL} -C -o ${LIBOWN} -g ${LIBGRP} -m ${LIBMODE} \
+		${.CURDIR}/libarchive.pc ${DESTDIR}${LIBDATADIR}/pkgconfig
+.endif
+
 .PATH: ${LIBARCHIVEDIR}/libarchive
 
 # Headers to be installed in /usr/include

lib/libarchive/libarchive.pc

@@ -0,0 +1,12 @@
+# $FreeBSD$
+prefix=/usr
+exec_prefix=${prefix}
+libdir=${exec_prefix}/lib
+includedir=${prefix}/include
+
+Name: libarchive
+Description: library that can create and read several streaming archive formats
+Version: 3.1.2
+Cflags: -I${includedir}
+Libs: -L${libdir} -larchive
+Libs.private: -lz -lbz2 -llzma -lbsdxml -lcrypto