Subzero: Use a "known" version of clang-format.

src/assembler.h

Index: src/assembler.h
diff --git a/src/assembler.h b/src/assembler.h
index 7997865ac742b8c911dc72c47dc0d270a110c97c..40f50fd5b1a11f3d0d79dffc40926124a98f200c 100644
--- a/src/assembler.h
+++ b/src/assembler.h
@@ -57,9 +57,7 @@ public:
   }
 
   // Emit a fixup at the current location.
-  void EmitFixup(AssemblerFixup *fixup) {
-    fixup->set_position(Size());
-  }
+  void EmitFixup(AssemblerFixup *fixup) { fixup->set_position(Size()); }
 
   // Get the size of the emitted code.
   intptr_t Size() const { return cursor_ - contents_; }