hg: graal/graal-compiler: Update Truffle version.

[doug.simon at oracle.com]

Changeset: d1a5115ea68d
Author:    Chris Seaton <chris.seaton at oracle.com>
Date:      2015-12-17 11:45 +0000
URL:       http://hg.openjdk.java.net/graal/graal-compiler/rev/d1a5115ea68d

Update Truffle version.

! mx.graal/suite.py