Add patch 'load-fast-borrowed-opt'

Summary:
This diff adds a patch to the `3.14` Meta-internal fork.

Fix issue where LOAD_FAST_BORROWED doesn't get applied past an empty basic block

Reviewed By: itamaro

Differential Revision: D81341134

fbshipit-source-id: 54c02f6604c0e5e0a638722ebec4a5586fd82c5e

Author: DinoV

Python/flowgraph.c

@@ -2982,10 +2982,8 @@ optimize_load_fast(cfg_builder *g)
 
         // Push fallthrough block
         cfg_instr *term = basicblock_last_instr(block);
-        if (term != NULL && block->b_next != NULL &&
-            !(IS_UNCONDITIONAL_JUMP_OPCODE(term->i_opcode) ||
-              IS_SCOPE_EXIT_OPCODE(term->i_opcode))) {
-            assert(BB_HAS_FALLTHROUGH(block));
+        if (BB_HAS_FALLTHROUGH(block)) {
+            assert(block->b_next != NULL);
             load_fast_push_block(&sp, block->b_next, refs.size);
         }