meson: Actually listen to docs option

meson.build

@@ -49,6 +49,11 @@ openhmd_required = false
 # Adding dependencies
 #
 
+doxygen = find_program('doxygen', required: get_option('docs'))
+if get_option('docs').enabled() or get_option('docs').auto()
+	build_docs = true
+endif
+
 glslangValidator = find_program('glslangValidator')
 
 avcodec = dependency('libavcodec', required: false)
@@ -67,8 +72,6 @@ if not opencv.found()
 	opencv = dependency('opencv', required: get_option('tracking'))
 endif
 
-doxygen = find_program('doxygen', required: get_option('docs'))
-
 pthreads = cc.find_library('pthread', required: true)
 
 if get_option('tracking').enabled() or get_option('tracking').auto()
@@ -171,10 +174,6 @@ if sdl2.found()
 	add_project_arguments('-DXRT_HAVE_SDL2', language: ['c', 'cpp'])
 endif
 
-if doxygen.found()
-	build_docs = true
-endif
-
 
 #
 # Go down sub directories