Generate the class given in class if not explicitly given (libwacom#790)

This is still a part of the API, and thus have required even new .tablet
files to fill this out even though it's superseded by IntegratedIn. So
let's generate them programmatically.

This turns devices that are IntegratedIn=Display to the Cintiq class,
IntegratedIn=Display;System into the ISDV4 class, and everything else
into the Bamboo class.

data/wacom-cintiq-24hd-touch.tablet

@@ -44,7 +44,6 @@ Name=Wacom Cintiq 24HD touch
 ModelName=DTH-2400
 DeviceMatch=usb|056a|00f8
 PairedID=usb|056a|00f6
-Class=Cintiq
 Width=21
 Height=13
 Layout=wacom-cintiq-24hd.svg

data/wacom-cintiq-27hdt.tablet

@@ -9,7 +9,6 @@ Name=Wacom Cintiq 27QHD touch
 ModelName=DTH-2700
 DeviceMatch=usb|056a|032b
 PairedID=usb|056a|032c
-Class=Cintiq
 Width=24
 Height=12
 Styli=@intuos5;@propengen2;

libwacom/libwacom.c

@@ -1362,7 +1362,17 @@ libwacom_get_height(const WacomDevice *device)
 LIBWACOM_EXPORT WacomClass
 libwacom_get_class(const WacomDevice *device)
 {
-	return device->cls;
+	if (device->cls != WCLASS_UNKNOWN) {
+		return device->cls;
+	}
+	if (device->integration_flags & WACOM_DEVICE_INTEGRATED_DISPLAY &&
+		device->integration_flags & WACOM_DEVICE_INTEGRATED_SYSTEM) {
+		return WCLASS_ISDV4;
+	}
+	if (device->integration_flags & WACOM_DEVICE_INTEGRATED_DISPLAY) {
+		return WCLASS_CINTIQ;
+	}
+	return WCLASS_BAMBOO;
 }
 
 LIBWACOM_EXPORT int

test/test-load.c

@@ -202,6 +202,7 @@ test_cintiq24hdt(struct fixture *f, gconstpointer user_data)
 	const WacomMatch *match;
 
 	g_assert_nonnull(device);
+	g_assert_cmpint(libwacom_get_class(device), ==, WCLASS_CINTIQ);
 
 	/* 24HDT has one paired device */
 	match = libwacom_get_paired_device(device);