Add upstream information to libraries

extern/ceres/README.blender

@@ -0,0 +1,4 @@
+Project: Ceres Solver
+URL: http://ceres-solver.org/
+Upstream version 1.11 (aef9c9563b08d5f39eee1576af133a84749d1b48)
+Local modifications: None

extern/clew/README.blender

@@ -0,0 +1,5 @@
+Project: OpenCL Wrangler
+URL: https://github.com/OpenCLWrangler/clew
+License: Apache 2.0
+Upstream version: 277db43
+Local modifications: None

extern/cuew/README.blender

@@ -0,0 +1,5 @@
+Project: Cuda Wrangler
+URL: https://github.com/CudaWrangler/cuew
+License: Apache 2.0
+Upstream version: e2e0315
+Local modifications: None

extern/gflags/README.blender

@@ -1,5 +1,5 @@
 Project: Google Flags
-URL: http://code.google.com/p/google-gflags/
+URL: https://github.com/gflags/gflags
 License: New BSD
 Upstream version: 2.2.0 (9db82895)
 Local modifications:
@@ -17,3 +17,7 @@ Local modifications:
 
 - Applied some modifications from fork https://github.com/Nazg-Gul/gflags.git
   (see https://github.com/gflags/gflags/pull/129)
+
+- Avoid attemot of acquiring mutex lock in FlagRegistry::GlobalRegistry when
+  doing static flags initialization. See d81dd2d in Blender repository.
+

extern/glog/README.blender

@@ -1,5 +1,5 @@
 Project: Google Logging
-URL: http://code.google.com/p/google-glog/
+URL: https://github.com/google/glog
 License: New BSD
 Upstream version: 0.3.4, 4d391fe
 Local modifications:

extern/gtest/README.blender

@@ -1,7 +1,5 @@
 Project: Google C++ Testing Framework
-URL: http://code.google.com/p/googletest
+URL: https://github.com/google/googletest
 License: New BSD
 Upstream version: 1.7.0
-Local modifications:
-
-None.
+Local modifications:None