src: Adding pkgconfig script, so apps can use pkg-config to get all necesasry parameters to compile against the library

Change-Id: Ie19fc258c2602a3f0685c247e328e9d3166639dc
diff --git a/.gitignore b/.gitignore
index db21ec6..35c2f84 100644
--- a/.gitignore
+++ b/.gitignore
@@ -81,3 +81,5 @@
 examples/consumer
 examples/producer
 
+# pkg-config file
+libndn-cpp-dev.pc