meson: add option for tracing

meson_options.txt

@@ -93,6 +93,12 @@ option('service',
 	description: 'Enable separate service module for OpenXR runtime'
 )
 
+option('tracing',
+	type: 'boolean',
+	value: false,
+	description: 'Enable Perfetto/Percetto tracing'
+)
+
 option('layer_depth',
 	type: 'boolean',
 	value: true,

src/xrt/include/xrt/meson.build

@@ -124,6 +124,10 @@ if get_option('service')
 	build_conf.set('XRT_FEATURE_SERVICE', true)
 endif
 
+if get_option('tracing')
+	build_conf.set('XRT_FEATURE_TRACING', true)
+endif
+
 if get_option('color_log')
 	build_conf.set('XRT_FEATURE_COLOR_LOG', true)
 endif