svnversion breaking build

[MelFlynn]

# HG changeset patch
# User Mel Flynn
# Date 1338060896 -7200
# Branch upstream
# Node ID b6769c1588b2c6c5a2e221b448ae7e2f78b6aa72
# Parent fe8fd18df7af79bc99b7d9d66aeeafe83952012d
Fix builds that aren't using versioned subversion repos but have svnversion
in $PATH.
It will result in the rather cryptic compiler error:
Unknown identifier: Unversioned

somewhere in ECDatabaseMySQL.cpp, pending your build options.