package/wpewebkit: disable libdrm usage when not available

Pass USE_LIBDRM=OFF to the wpewebkit CMake configuration step when the
libdrm package has not been selected.

WPE WebKit can be built without libdrm support, and it will still work
with backends that use other platform-specific methods to handle
graphics buffers and/or presenting content onto an output. For example
this is the case with wpebackend-rdk configured to use rpi-userland,
which uses dispmanx to produce the output instead of DRM/KMS.

Signed-off-by: Adrian Perez de Castro <aperez@igalia.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 65f8174648a3df922892cfac1ad15279d1bffde3)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/wpewebkit/wpewebkit.mk

@@ -87,6 +87,13 @@ else
 WPEWEBKIT_CONF_OPTS += -DUSE_LIBBACKTRACE=OFF
 endif
 
+ifeq ($(BR2_PACKAGE_LIBDRM),y)
+WPEWEBKIT_CONF_OPTS += -DUSE_LIBDRM=ON
+WPEWEBKIT_DEPENDENCIES += libdrm
+else
+WPEWEBKIT_CONF_OPTS += -DUSE_LIBDRM=OFF
+endif
+
 ifeq ($(BR2_PACKAGE_WOFF2),y)
 WPEWEBKIT_CONF_OPTS += -DUSE_WOFF2=ON
 WPEWEBKIT_DEPENDENCIES += woff2