build-sys: add .pc file for libsystemd-bus

Makefile.am

@@ -1992,7 +1992,11 @@ libsystemd_bus_la_LDFLAGS = \
 	-version-info $(LIBSYSTEMD_BUS_CURRENT):$(LIBSYSTEMD_BUS_REVISION):$(LIBSYSTEMD_BUS_AGE) \
 	-Wl,--version-script=$(top_srcdir)/src/libsystemd-bus/libsystemd-bus.sym
 
+pkgconfiglib_DATA += \
+	src/libsystemd-bus/libsystemd-bus.pc
+
 EXTRA_DIST += \
+	src/libsystemd-bus/libsystemd-bus.pc.in \
 	src/libsystemd-bus/libsystemd-bus.sym
 
 lib_LTLIBRARIES += \

src/libsystemd-bus/.gitignore

@@ -0,0 +1 @@
+/libsystemd-bus.pc

src/libsystemd-bus/libsystemd-bus.pc.in

@@ -0,0 +1,18 @@
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@
+
+Name: systemd
+Description: systemd Bus and Event Loop Library
+URL: @PACKAGE_URL@
+Version: @PACKAGE_VERSION@
+Libs: -L${libdir} -lsystemd-bus
+Cflags: -I${includedir}