Don't call realpath on a file that may not exist.

Otherwise realpath prints an error message.

bug: 25658944
Change-Id: I63145c3d955e088e53708d8c6add945e6eab6654
diff --git a/tools/art b/tools/art
index 1394a46..91d6e27 100644
--- a/tools/art
+++ b/tools/art
@@ -30,8 +30,9 @@
 }
 
 function find_libdir() {
+  # Get the actual file, $DALVIKVM may be a symbolic link.
   # Use realpath instead of readlink because Android does not have a readlink.
-  if [ "$(realpath "$ANDROID_ROOT/bin/$DALVIKVM")" = "$(realpath "$ANDROID_ROOT/bin/dalvikvm64")" ]; then
+  if [[ "$(realpath "$ANDROID_ROOT/bin/$DALVIKVM")" == *dalvikvm64 ]]; then
     echo "lib64"
   else
     echo "lib"