Upgrade internal CLANG version for FB-internal gcc 4.8.1

Summary: After removing two move operations, we can make CLANG 3.7 build pass under GCC 4.8.1.

Test Plan: USE_CLANG=1 ROCKSDB_FBCODE_BUILD_WITH_481=1 make all -j32

Reviewers: yhchiang, IslamAbdelRahman, rven, anthony

Reviewed By: anthony

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D52365

build_tools/fbcode_config4.8.1.sh

@@ -77,10 +77,10 @@ if [ -z "$USE_CLANG" ]; then
   CFLAGS+=" -isystem $LIBGCC_INCLUDE"
 else
   # clang 
-  CLANG_BASE="/mnt/gvfs/third-party2/clang/ab054e9a490a8fd4537c0b6ec56e5c91c0f81c91/3.4"
+  CLANG_BASE="/mnt/gvfs/third-party2/clang/ab054e9a490a8fd4537c0b6ec56e5c91c0f81c91/3.7"
-  CLANG_INCLUDE="$CLANG_BASE/gcc-4.8.1-glibc-2.17/fb0f730/lib/clang/3.4/include"
+  CLANG_INCLUDE="$CLANG_BASE/gcc-4.8.1-glibc-2.17/ee9b060/lib/clang/3.7/include"
-  CC="$CLANG_BASE/centos6-native/9cefd8a/bin/clang"
+  CC="$CLANG_BASE/centos6-native/b2feaee/bin/clang"
-  CXX="$CLANG_BASE/centos6-native/9cefd8a/bin/clang++"
+  CXX="$CLANG_BASE/centos6-native/b2feaee/bin/clang++"
 
   KERNEL_HEADERS_INCLUDE="/mnt/gvfs/third-party2/kernel-headers/1a48835975c66d30e47770ec419758ed3b9ba010/3.10.62-62_fbk17_03959_ge29cc63/gcc-4.8.1-glibc-2.17/da39a3e/include/"
 

db/db_bench.cc

@@ -2392,8 +2392,7 @@ class Benchmark {
         fprintf(stderr, "Open flash device failed\n");
         exit(1);
       }
-      flashcache_aware_env_ =
+      flashcache_aware_env_ = NewFlashcacheAwareEnv(FLAGS_env, cachedev_fd_);
-          std::move(NewFlashcacheAwareEnv(FLAGS_env, cachedev_fd_));
       if (flashcache_aware_env_.get() == nullptr) {
         fprintf(stderr, "Failed to open flashcache device at %s\n",
                 FLAGS_flashcache_dev.c_str());
@@ -3053,7 +3052,7 @@ class Benchmark {
     std::vector<std::unique_ptr<const char[]> > key_guards;
     std::vector<std::string> values(entries_per_batch_);
     while (static_cast<int64_t>(keys.size()) < entries_per_batch_) {
-      key_guards.push_back(std::move(std::unique_ptr<const char[]>()));
+      key_guards.push_back(std::unique_ptr<const char[]>());
       keys.push_back(AllocateKey(&key_guards.back()));
     }