Again to fix compilation after b0afad8f0b6a3be7ab3a23e063b0201cd68ada95

Commit 125bb81bef7729d182f533989ffdf53685abbe31 wasn't enough. Let's
just make it simpler and use a regular function.

Change-Id: I9627dedaa87873b4b138224afd182e4fd9a55265
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Ensure we try the UTF-8 conversions with longer strings

The SSE2-based conversion only kicks in with strings with 8 characters
or more in length.

Change-Id: Ic1daad0845571be03547553cc001d83550f0c89c
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
configure: gtk style related cosmetical fixes

* add -help text for gtkstyle
* use capital GTK in warning message for consistency

Change-Id: Iff522cc49497dda406dd111594857930d82e4231
Reviewed-by: Martin Jansa <Martin.Jansa@gmail.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>