Fix build on FreeBSD after qtermwidgets update

After qtermwidgets has been updated in the GRASS provider, the build on FreeBSD is broken with the following error:

.../src/plugins/grass/qtermwidgets/kpty.cpp:98:11:fatal error:'utmp.h' file not found.

The patch circumstances this 'classic' utempter problem on FreeBSD.

src/plugins/grass/qtermwidget/kpty.cpp

@@ -30,6 +30,7 @@
 #if defined(__FreeBSD__) || defined(__DragonFly__)
 #define HAVE_LOGIN
 #define HAVE_LIBUTIL_H
+#define HAVE_UTEMPTER
 #endif
 
 #if defined(__OpenBSD__)
@@ -92,6 +93,7 @@
 
 #ifdef HAVE_UTEMPTER
 extern "C" {
+# include <ulog.h>
 # include <utempter.h>
 }
 #else