PSync.pc.in: remove -lndn-cxx

Also change GPL to LGPL in README

Change-Id: I67249704b0b8e426d32543cb9fabaf40bfa66a9a
diff --git a/PSync.pc.in b/PSync.pc.in
index b50c7ac..e72112c 100644
--- a/PSync.pc.in
+++ b/PSync.pc.in
@@ -5,6 +5,6 @@
 Name: PSync
 Description: PSync library
 Version: @VERSION@
-Libs: -L${libdir} -lPSync -lndn-cxx
+Libs: -L${libdir} -lPSync
 Cflags: -I${includedir}