Move QGestureRecognizer test to widgets/kernel

It's the subdir where the implementation also lives. There's no
src/widgets/gestures, either.

Change the mac: into a darwin: scope in the .pro file, so Sanity Bot
does not complain.

Change-Id: I7608d6da05af4a1117db585798a87a20ae80717a
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

tests/auto/widgets/gestures/gestures.pro

@@ -1,6 +0,0 @@
-TEMPLATE=subdirs
-SUBDIRS=\
-   qgesturerecognizer \
-
-mac: SUBDIRS -= \ # Uses native recognizers
-   qgesturerecognizer \

tests/auto/widgets/kernel/kernel.pro

@@ -6,6 +6,7 @@ SUBDIRS=\
    qboxlayout \
    qdesktopwidget \
    qformlayout \
+   qgesturerecognizer \
    qgridlayout \
    qlayout \
    qstackedlayout \
@@ -19,4 +20,7 @@ SUBDIRS=\
    qshortcut \
    qsizepolicy
 
+darwin:SUBDIRS -= \ # Uses native recognizers
+   qgesturerecognizer \
+
 SUBDIRS -= qsound

tests/auto/widgets/widgets.pro

@@ -8,4 +8,3 @@ SUBDIRS=\
     styles \
     util \
     widgets \
-    gestures \