consider qt resource paths absolute

this fixes an assertion failure with qt4 mingw specs when PATH contains
a "." element.

Task-number: QTCREATORBUG-12528
Change-Id: I2b6b7e02cf38881d40bd78bb0d705f7d58d0736c
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>

src/shared/proparser/ioutils.cpp

@@ -64,6 +64,10 @@ bool IoUtils::isRelativePath(const QString &path)
 {
     if (path.startsWith(QLatin1Char('/')))
         return false;
+#ifdef QMAKE_BUILTIN_PRFS
+    if (path.startsWith(QLatin1String(":/")))
+        return false;
+#endif
 #ifdef Q_OS_WIN
     if (path.startsWith(QLatin1Char('\\')))
         return false;