[tests] Fix building the test libraries. (#7172)

Fix building the test libraries so that the native compiler gets passed the
right arguments (which makes us build the tvOS and watchOS versions of these
libraries with bitcode).

This fixes a build problem with the framework-test test for tvOS and watchOS.

Also remove an outdated comment.

tests/test-libraries/Makefile

@@ -82,7 +82,7 @@ EXTRA_DEPENDENCIES = libtest.h $(GENERATED_FILES) rename.h
 
 COMMON_DYLIB_ARGS=-g -dynamiclib -gdwarf-2 -fms-extensions libframework.m -o $$@ -Wall -framework Foundation -lz
 .libs/$(1)/libtest.%.dylib: libframework.m | .libs/$(1)
-	$$(call Q_2,CC,    [$(1)]) $$(XCODE_CC) $$(COMMON_DYLIB_ARGS) -arch $$(if $$(filter x86,$$*),i386,$$*) $(8) -isysroot $(XCODE_DEVELOPER_ROOT)/Platforms/$(4).platform/Developer/SDKs/$(4)$$($(6)_SDK_VERSION).sdk
+	$$(call Q_2,CC,    [$(1)]) $$(XCODE_CC) $$(COMMON_DYLIB_ARGS) -arch $$(if $$(filter x86,$$*),i386,$$*) $(5) -isysroot $(XCODE_DEVELOPER_ROOT)/Platforms/$(4).platform/Developer/SDKs/$(4)$$($(6)_SDK_VERSION).sdk
 	$$(Q) $(XCODE_DEVELOPER_ROOT)/Toolchains/XcodeDefault.xctoolchain/usr/bin/install_name_tool -id @rpath/XTest.framework/XTest $$@
 
 .libs/$(1)/libtest.dylib: $$(foreach arch,$(3),.libs/$(1)/libtest.$$(arch).dylib)
@@ -116,7 +116,6 @@ endef
 # 4: platform name
 # 5: min version
 # 6: os
-# 7: architectures as as passed to clang
 $(eval $(call Template,iphonesimulator,IOSSIMULATOR,x86 x86_64,iPhoneSimulator,-mios-simulator-version-min=8.0,IOS))
 $(eval $(call Template,iphoneos,IPHONEOS,armv7 armv7s arm64,iPhoneOS,-miphoneos-version-min=8.0,IOS))
 ifdef INCLUDE_TVOS