build: add v8 requirement to test-v8* in Makefile

The test targets expect that V8 is built in deps/v8/out

Ref: nodejs#7477

Makefile

@@ -232,22 +232,22 @@ test-timers-clean:
 
 
 ifneq ("","$(wildcard deps/v8/tools/run-tests.py)")
-test-v8:
+test-v8: v8
 	# note: performs full test unless QUICKCHECK is specified
 	deps/v8/tools/run-tests.py --arch=$(V8_ARCH) \
         --mode=$(BUILDTYPE_LOWER) $(V8_TEST_OPTIONS) $(QUICKCHECK_ARG) \
         --no-presubmit \
         --shell-dir=$(PWD)/deps/v8/out/$(V8_ARCH).$(BUILDTYPE_LOWER) \
 	 $(TAP_V8)
 
-test-v8-intl:
+test-v8-intl: v8
 	# note: performs full test unless QUICKCHECK is specified
 	deps/v8/tools/run-tests.py --arch=$(V8_ARCH) \
         --mode=$(BUILDTYPE_LOWER) --no-presubmit $(QUICKCHECK_ARG) \
         --shell-dir=deps/v8/out/$(V8_ARCH).$(BUILDTYPE_LOWER) intl \
         $(TAP_V8_INTL)
 
-test-v8-benchmarks:
+test-v8-benchmarks: v8
 	deps/v8/tools/run-tests.py --arch=$(V8_ARCH) --mode=$(BUILDTYPE_LOWER) \
         --download-data $(QUICKCHECK_ARG) --no-presubmit \
         --shell-dir=deps/v8/out/$(V8_ARCH).$(BUILDTYPE_LOWER) benchmarks \