Add pkg-config file

Makefile

@@ -1,4 +1,6 @@
 LIB=	stdthreads
+PACKAGE_VERSION?=	0.2
+PREFIX?=	/usr
 
 HDR=	threads.h
 SRCS=	threads.h call_once.c cnd.c mtx.c thrd.c tss.c
@@ -17,4 +19,22 @@ includes:
             echo $$j; \
             eval "$$j"; \
 
+stdthreads.pc: stdthreads.pc.in
+	@sed -e 's#@prefix@#${PREFIX}#g' \
+		-e 's#@exec_prefix@#$${prefix}#g' \
+		-e 's#@libdir@#$${exec_prefix}/lib#g' \
+		-e 's#@includedir@#$${prefix}/include#g' \
+		-e 's#@PACKAGE_VERSION@#'${PACKAGE_VERSION}'#g' \
+	< ${.CURDIR}/stdthreads.pc.in > $@
+
+all:	stdthreads.pc
+
+CLEANFILES+=	stdthreads.pc
+
+install-pc:	stdthreads.pc
+	${INSTALL} ${INSTALL_COPY} -o ${BINOWN} -g ${BINGRP} -m 444 \
+		stdthreads.pc ${LIBDIR}/pkgconfig
+
+realinstall:	install-pc
+
 .include <bsd.lib.mk>