remove CFG_RELEASE from the Makefile

The previous commit made this unused; much of the logic for assigning to
this variable now lives in Cargo itself.

Author: froydnj

Makefile.in

@@ -9,16 +9,12 @@ include config.mk
 export PATH := $(dir $(CFG_RUSTC)):$(PATH)
 
 ifeq ($(CFG_RELEASE_CHANNEL),stable)
-CFG_RELEASE=$(CFG_RELEASE_NUM)
 CFG_PACKAGE_VERS=$(CFG_RELEASE_NUM)
 else ifeq ($(CFG_RELEASE_CHANNEL),beta)
-CFG_RELEASE=$(CFG_RELEASE_NUM)-beta$(CFG_PRERELEASE_VERSION)
 CFG_PACKAGE_VERS=beta
 else ifeq ($(CFG_RELEASE_CHANNEL),nightly)
-CFG_RELEASE=$(CFG_RELEASE_NUM)-nightly
 CFG_PACKAGE_VERS=nightly
 else ifeq ($(CFG_RELEASE_CHANNEL),dev)
-CFG_RELEASE=$(CFG_RELEASE_NUM)-dev
 CFG_PACKAGE_VERS=$(CFG_RELEASE_NUM)-dev
 endif