Introduce ro.build.version.known_codenames sysprop.

It defines values for Build.VERSION.KNOWN_CODENAMES constant, and should
contain all codenames starting from Q, including current codename
for in development branches.

Bug: 211747008
Test: presubmit
Change-Id: If8995750e369ba39bfc7041580c21b2f96632a78
diff --git a/core/sysprop.mk b/core/sysprop.mk
index 12ead6e..86435d96 100644
--- a/core/sysprop.mk
+++ b/core/sysprop.mk
@@ -270,6 +270,7 @@
 	        PLATFORM_PREVIEW_SDK_FINGERPRINT="$$(cat $(API_FINGERPRINT))" \
 	        PLATFORM_VERSION_CODENAME="$(PLATFORM_VERSION_CODENAME)" \
 	        PLATFORM_VERSION_ALL_CODENAMES="$(PLATFORM_VERSION_ALL_CODENAMES)" \
+	        PLATFORM_VERSION_KNOWN_CODENAMES="$(PLATFORM_VERSION_KNOWN_CODENAMES)" \
 	        PLATFORM_MIN_SUPPORTED_TARGET_SDK_VERSION="$(PLATFORM_MIN_SUPPORTED_TARGET_SDK_VERSION)" \
 	        BUILD_VERSION_TAGS="$(BUILD_VERSION_TAGS)" \
 	        $(if $(OEM_THUMBPRINT_PROPERTIES),BUILD_THUMBPRINT="$(BUILD_THUMBPRINT_FROM_FILE)") \