Remove PLATFORM_VERSION_FUTURE_CODENAMES

It has been wrong to split ALL_VERSIONS into exclusive two sets of
before/after TARGET_PLATFORM_VERSION.

And PLATFORM_VERSION_ALL_CODENAMES supports all *active* list of
non-finalized codenames.

Bug: 152960049
Test: m
Merged-In: I1e87206a7f261e587cf079cb6b7025ca16aa4fe4
Change-Id: I1e87206a7f261e587cf079cb6b7025ca16aa4fe4
(cherry picked from commit abe575d17b2940cd91f324882733882f2957b7f8)

Exempt-From-Owner-Approval: cp from master
Change-Id: I1e87206a7f261e587cf079cb6b7025ca16aa4fe4
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 811bcd8..fe71d7b 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -123,8 +123,8 @@
     PLATFORM_VERSION_CODENAME := $(TARGET_PLATFORM_VERSION)
   endif
 
-  # This is all of the *active* development codenames. There are future
-  # codenames not included in this list. This confusing name is needed because
+  # This is all of the *active* development codenames.
+  # This confusing name is needed because
   # all_codenames has been baked into build.prop for ages.
   #
   # Should be either the same as PLATFORM_VERSION_CODENAME or a comma-separated
@@ -141,29 +141,14 @@
     $(if $(filter $(_codename),$(PLATFORM_VERSION_ALL_CODENAMES)),,\
       $(eval PLATFORM_VERSION_ALL_CODENAMES += $(_codename))))
 
-  # This is all of the inactive development codenames. Available to be targeted
-  # in this branch but in the future relative to our current target.
-  PLATFORM_VERSION_FUTURE_CODENAMES :=
-
-  # Build a list of all untargeted code names. Avoid duplicates.
-  _versions_not_in_target := \
-    $(filter-out $(PLATFORM_VERSION_ALL_CODENAMES),$(ALL_VERSIONS))
-  $(foreach version,$(_versions_not_in_target),\
-    $(eval _codename := $(PLATFORM_VERSION_CODENAME.$(version)))\
-    $(if $(filter $(_codename),$(PLATFORM_VERSION_FUTURE_CODENAMES)),,\
-      $(eval PLATFORM_VERSION_FUTURE_CODENAMES += $(_codename))))
-
   # And convert from space separated to comma separated.
   PLATFORM_VERSION_ALL_CODENAMES := \
     $(subst $(space),$(comma),$(strip $(PLATFORM_VERSION_ALL_CODENAMES)))
-  PLATFORM_VERSION_FUTURE_CODENAMES := \
-    $(subst $(space),$(comma),$(strip $(PLATFORM_VERSION_FUTURE_CODENAMES)))
 
 endif
 .KATI_READONLY := \
   PLATFORM_VERSION_CODENAME \
-  PLATFORM_VERSION_ALL_CODENAMES \
-  PLATFORM_VERSION_FUTURE_CODENAMES
+  PLATFORM_VERSION_ALL_CODENAMES
 
 ifeq (REL,$(PLATFORM_VERSION_CODENAME))
   PLATFORM_PREVIEW_SDK_VERSION := 0