Allow filter calls with a list as a pattern

This commit doesn't attempt to replace the filter
calls with anything more idomatic for now.

It also removes the case for filter-out, because
the actual function name is filter_out and wasn't
being used anyways. Even if I were to change it
to filter_out, that would produce buggy results:

ifneq (,$(filter $(TARGET_BUILD_VARIANT), userdebug eng))
endif
ifneq (,$(filter-out $(TARGET_BUILD_VARIANT), userdebug eng))
endif

Both of these would produce:

if g["TARGET_BUILD_VARIANT"] in ["userdebug", "eng"]:
  pass

Fixes: 218702402
Test: go test
Change-Id: I566079e5d3a364c42db14045aa1bab9d99eba05f
diff --git a/mk2rbc/mk2rbc_test.go b/mk2rbc/mk2rbc_test.go
index 2083121..55e37fe 100644
--- a/mk2rbc/mk2rbc_test.go
+++ b/mk2rbc/mk2rbc_test.go
@@ -389,6 +389,10 @@
 endif
 ifeq ($(TARGET_BUILD_VARIANT), $(filter $(TARGET_BUILD_VARIANT), userdebug eng))
 endif
+ifneq (, $(filter $(TARGET_BUILD_VARIANT), userdebug eng))
+endif
+ifneq (,$(filter userdebug eng, $(TARGET_BUILD_VARIANT)))
+endif
 ifneq (,$(filter true, $(v1)$(v2)))
 endif
 ifeq (,$(filter barbet coral%,$(TARGET_PRODUCT)))
@@ -407,8 +411,12 @@
     pass
   if "plaf" in g.get("PLATFORM_LIST", []):
     pass
+  if g["TARGET_BUILD_VARIANT"] == " ".join(rblf.filter(g["TARGET_BUILD_VARIANT"], "userdebug eng")):
+    pass
   if g["TARGET_BUILD_VARIANT"] in ["userdebug", "eng"]:
     pass
+  if rblf.filter("userdebug eng", g["TARGET_BUILD_VARIANT"]):
+    pass
   if rblf.filter("true", "%s%s" % (_v1, _v2)):
     pass
   if not rblf.filter("barbet coral%", g["TARGET_PRODUCT"]):