Source Common in check-prereqs.sh

Fixes #671

scripts/test/check-prereqs.sh

@@ -4,9 +4,19 @@
 # Licensed under the MIT license. See LICENSE file in the project root for full license information.
 #
 
+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 ! type -p cmake >/dev/null; then
     error "cmake is required to build the native host 'corehost'"
     error "OS X w/Homebrew: 'brew install cmake'"
     error "Ubuntu: 'sudo apt-get install cmake'"
     exit 1
-fi
+fi