Generate zlib.pc from source.

Reviewed by:		bapt
MFC after:		3 days
Differential Revision:	https://reviews.freebsd.org/D24806

lib/libz/Makefile

@@ -53,6 +53,17 @@ INCS=		zconf.h zlib.h
 
 .PATH:		${ZLIBSRC}/test
 
+ZLIB_VERSION!=	sed -n '/define.*ZLIB_VERSION/{s,[^0-9.],,gp;q;}' ${ZLIBSRC}/zlib.h
+
+zlib.pc: zlib.pc.in
+	sed -e 's,@prefix@,/usr,g ; \
+		s,@exec_prefix@,$${prefix},g ; \
+		s,@libdir@,$${exec_prefix}/lib,g ; \
+		s,@sharedlibdir@,$${libdir},g ; \
+		s,@includedir@,$${prefix}/include,g ; \
+		s,@VERSION@,${ZLIB_VERSION},g ;' \
+		${.ALLSRC} > ${.TARGET}
+
 minigzip:	all minigzip.o
 	$(CC) -o minigzip minigzip.o -L. -lz
 

lib/libz/zlib.pc

@@ -1,14 +0,0 @@
-# $FreeBSD$
-prefix=/usr
-exec_prefix=${prefix}
-libdir=${exec_prefix}/lib
-sharedlibdir=${libdir}
-includedir=${prefix}/include
-
-Name: zlib
-Description: zlib compression library
-Version: 1.2.10
-
-Requires:
-Libs: -L${libdir} -L${sharedlibdir} -lz
-Cflags: -I${includedir}