Remove CAFFE2_USE_MINIMAL_GOOGLE_GLOG (pytorch#12938)

Summary:
Pull Request resolved: pytorch#12938

We will be using C10_USE_MINIMAL_GLOG. Also, this will be in exported flags,
so dependent libraries won't need to define it.

Reviewed By: smessmer, BIT-silence

Differential Revision: D10468993

fbshipit-source-id: 04ae3ae17122d46b1b512d4202ab014365b87f4a

c10/util/logging_is_google_glog.h

@@ -16,7 +16,7 @@
 #include <cuda.h>
 #endif
 
-#if !defined(__CUDACC__) && !defined(CAFFE2_USE_MINIMAL_GOOGLE_GLOG)
+#if !defined(__CUDACC__) && !defined(C10_USE_MINIMAL_GLOG)
 #include <glog/stl_logging.h>
 
 // Old versions of glog don't declare this using declaration, so help
@@ -26,7 +26,7 @@ namespace std {
 using ::operator<<;
 }
 
-#else // !defined(__CUDACC__) && !defined(CAFFE2_USE_MINIMAL_GOOGLE_GLOG)
+#else // !defined(__CUDACC__) && !defined(C10_USE_MINIMAL_GLOG)
 
 // In the cudacc compiler scenario, we will simply ignore the container
 // printout feature. Basically we need to register a fake overload for