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

[doug.simon at oracle.com]

Changeset: c1e6ec246708
Author:    Christian Humer <christian.humer at oracle.com>
Date:      2015-10-20 18:32 +0200
URL:       http://hg.openjdk.java.net/graal/graal-compiler/rev/c1e6ec246708

Update Truffle version.

! mx.graal/suite.py