Compilation error on stable with Qt 5.4 in GuiLog.cpp

[Jean-Marc Lasgouttes]

Hi there,

There is compilation error when compiling stable branch on ubuntu 15.10: 
at GuiLog::goTo, the code uses

QTextCursor QTextDocument::find(const QRegularExpression &expr, const 
QTextCursor &cursor, QTextDocument::FindFlags options = FindFlags()) const

This has been introduced in Qt 5.5, according to the docs, and I only 
have Qt 5.4 here.

JMarc