Kotlin: Remove unused var SEMMLE_PLATFORM_TOOLS

Author: igfoo

java/kotlin-extractor/src/main/java/com/semmle/util/process/Env.java

@@ -185,10 +185,6 @@ public enum Var {
 		 * The platform we are running on; one of "linux", "osx" and "win".
 		 */
 		SEMMLE_PLATFORM,
-		/**
-		 * Location of platform specific tools, currently only used in universal LGTM distributions
-		 */
-		SEMMLE_PLATFORM_TOOLS,
 		/**
 		 * PATH to use to look up tooling required by macOS Relocator scripts.
 		 */