Revert D28461013: [nnc] Enable CPU fusion inside Facebook, take 2

Test Plan: revert-hammer

Differential Revision:
D28461013 (pytorch@c76405d)

Original commit changeset: 79a80b6ffb65

fbshipit-source-id: d9cc5c512542153f39664635fb080d797a9de7d0

torch/csrc/jit/codegen/fuser/interface.cpp

@@ -8,13 +8,8 @@
 #include <c10/util/Flags.h>
 #include <stdexcept>
 
-#ifdef FBCODE_CAFFE2
-// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
-C10_DEFINE_bool(torch_jit_enable_cpu_fusion, true, "enable cpu fusion");
-#else
 // NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
 C10_DEFINE_bool(torch_jit_enable_cpu_fusion, false, "enable cpu fusion");
-#endif
 
 namespace torch {
 namespace jit {
@@ -51,7 +46,6 @@ bool canFuseOnGPU() {
 
 void overrideCanFuseOnCPU(bool value) {
   detail::cpu_fuser_enabled = value;
-  FLAGS_torch_jit_enable_cpu_fusion = value;
 }
 
 void overrideCanFuseOnGPU(bool value) {