Glog/gflags: Reduce amount of local modifications

With better directory layout and more proper include
statements we can avoid several local modifications,
such as changing config.h for Windows Glog and the
ones related on pass-through statements in logging
headers in Glog.

This commit also makes unused functions not-a-warning
for external code.

extern/gflags/README.blender

@@ -17,10 +17,5 @@ Local modifications:
 - Applied some modifications from fork https://github.com/Nazg-Gul/gflags.git
   (see https://github.com/gflags/gflags/pull/129)
 
-- Made `google::{anonymous}::FlagValue::ValueSize() const` inlined, so it does
-  not trigger strict compiler warning.
-
-- Did the same for CommandLineFlagParser::ValidateFlags().
-
 - Ifdef-ed __attribute((unused)) in gflags.h.
   This file is compile-time configurable in upstream, so can not avoid change here.

extern/gflags/src/gflags.cc

@@ -225,7 +225,7 @@ class FlagValue {
   bool Equal(const FlagValue& x) const;
   FlagValue* New() const;   // creates a new one with default value
   void CopyFrom(const FlagValue& x);
-  inline int ValueSize() const;
+  int ValueSize() const;
 
   // Calls the given validate-fn on value_buffer_, and returns
   // whatever it returns.  But first casts validate_fn_proto to a
@@ -485,7 +485,7 @@ void FlagValue::CopyFrom(const FlagValue& x) {
   }
 }
 
-inline int FlagValue::ValueSize() const {
+int FlagValue::ValueSize() const {
   if (type_ > FV_MAX_INDEX) {
     assert(false);  // unknown type
     return 0;
@@ -1257,7 +1257,7 @@ void CommandLineFlagParser::ValidateFlags(bool all) {
   }
 }
 
-inline void CommandLineFlagParser::ValidateAllFlags() {
+void CommandLineFlagParser::ValidateAllFlags() {
   ValidateFlags(true);
 }
 

extern/gflags/src/gflags_completions.cc

@@ -55,8 +55,6 @@
 #include <utility>
 #include <vector>
 
-#include "gflags_completions.h"
-
 #include "config.h"
 #include "gflags/gflags.h"
 #include "gflags/gflags_completions.h"