Update project URLs to use libffi/libffi

README

@@ -183,7 +183,7 @@ To install the library and header files, type "make install".
 History
 =======
 
-See the git log for details at http://github.com/atgreen/libffi.
+See the git log for details at http://github.com/libffi/libffi.
 
 4.0 TBD
         New API in support of GO closures.

configure.ac

@@ -2,7 +2,7 @@ dnl Process this with autoconf to create configure
 
 AC_PREREQ(2.68)
 
-AC_INIT([libffi], [3.99999], [http://github.com/atgreen/libffi/issues])
+AC_INIT([libffi], [3.99999], [http://github.com/libffi/libffi/issues])
 AC_CONFIG_HEADERS([fficonfig.h])
 
 AC_CANONICAL_SYSTEM