Bump CoreFx to rc2-23808

Workaround for issue 1294

Improve crossgen notifications

scripts/clean/clear-nuget-cache.sh

@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+#
+# Copyright (c) .NET Foundation and contributors. All rights reserved.
+# Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#
+
+set -e
+
+SOURCE="${BASH_SOURCE[0]}"
+while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
+  DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
+  SOURCE="$(readlink "$SOURCE")"
+  [[ "$SOURCE" != /* ]] && SOURCE="$DIR/$SOURCE" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
+done
+DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
+
+source "$DIR/../common/_common.sh"
+
+if [ ! -z "$CI_BUILD" ]; then
+	# periodically clear out the package cache on the CI server
+	PackageCacheFile="$NUGET_PACKAGES/packageCacheTime.txt"
+	if [ ! -f $PackageCacheFile ]; then
+		date > $PackageCacheFile
+	else
+		#$NUGET_PACKAGES_CACHE_TIME_LIMIT is in hours
+		CacheTimeLimitInSeconds=$(($NUGET_PACKAGES_CACHE_TIME_LIMIT * 3600))
+		CacheExpireTime=$(($(date +%s) - $CacheTimeLimitInSeconds))
+
+		if [ $(date +%s -r $PackageCacheFile) -lt $CacheExpireTime ]; then
+			header "Clearing package cache"
+
+			rm -Rf $NUGET_PACKAGES
+			mkdir -p $NUGET_PACKAGES
+			date > $PackageCacheFile
+		fi
+	fi
+fi