add pkgconfig file

Change-Id: I8948adf1e15a2baad3d67400d8940902807bf9ed
diff --git a/dhtnet.pc.in b/dhtnet.pc.in
new file mode 100644
index 0000000..1e3faa6
--- /dev/null
+++ b/dhtnet.pc.in
@@ -0,0 +1,10 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@
+Name: dhtnet
+Description: C++ peer to peer networking library
+Version: @VERSION@
+Requires: opendht >= 2.6
+Requires.private: pjproject
+Cflags: -I${includedir}