[make] do not overwrite execs in infer/bin/ when testing byte compilation

Summary:
We shouldn't install byte-executables unless the user types `make byte`.
Othewise everything gets very slow and the cause is not obvious.

Reviewed By: jeremydubreil

Differential Revision: D4779135

fbshipit-source-id: 757bfa2

Makefile

@@ -158,7 +158,10 @@ test_build: clang_plugin
 ifeq ($(IS_FACEBOOK_TREE),yes)
 	$(QUIET)$(MAKE) -C facebook setup
 endif
-	$(QUIET)$(MAKE) -C $(SRC_DIR) TEST=1 byte
+	$(QUIET)$(MAKE) -C $(SRC_DIR) TEST=1 byte_no_install
+#	byte_no_install builds most of what toplevel needs, so it's more efficient to run the
+#	toplevel build straight after it rather than in parallel. Note that both targets build files
+#	that the other doesn't.
 	$(QUIET)$(MAKE) -C $(SRC_DIR) TEST=1 toplevel
 
 .PHONY: ocaml_unit_test

infer/src/Makefile

@@ -269,6 +269,9 @@ endif
 .PHONY: byte
 byte: $(INFER_BIN).byte
 
+.PHONY: byte_no_install
+byte_no_install: $(INFER_BUILD_DIR)/$(INFER_MAIN).byte
+
 # to build only the single module <Module> (and its dependencies) with extra flags execute:
 #   make MFLAGS=<flags> M=<Module>.cm{o,x} module
 # for example, to build the assembly for the Ident module, execute