Don't depend on realpath being installed

pmd-dist/src/main/scripts/run.sh

@@ -62,7 +62,11 @@ java_heapsize_settings() {
 set_lib_dir() {
   if [ -z ${LIB_DIR} ]; then
     # Allow for symlinks to this script
-    local script_real_loc=$(realpath "$0")
+    if [ -L $0 ]; then
+      local script_real_loc=$(readlink "$0")
+    else
+      local script_real_loc=$0
+    fi
     local script_dir=$(dirname "${script_real_loc}")
     local cwd="${PWD}"