meson: move the "build this?" checks into the subdirs

Let's decide on what to build in the doc/ and test/ directory rather
than in the main file.

doc/meson.build

@@ -1,3 +1,7 @@
+if not get_option('documentation')
+    subdir_done()
+endif
+
 doxygen = find_program('doxygen', required : false)
 if not doxygen.found()
 	error('Program "doxygen" not found or not executable. Try building with -Ddocumentation=false')

meson.build

@@ -62,18 +62,12 @@ config_h.set10('HAVE_LIBXKBCOMMON', dep_libxkbcommon.found())
 dep_libevdev = dependency('libevdev', required: false)
 config_h.set10('HAVE_LIBEVDEV', dep_libevdev.found())
 dep_systemd = dependency('libsystemd', required: get_option('liboeffis'))
+configure_file(output: 'config.h', configuration: config_h)
 
 subdir('proto')
 subdir('src')
 subdir('tools')
+subdir('test')
+subdir('doc')
 
-# tests
-if get_option('tests')
-    subdir('test')
-endif
 
-configure_file(output: 'config.h', configuration: config_h)
-
-if get_option('documentation')
-    subdir('doc')
-endif

test/meson.build

@@ -1,3 +1,7 @@
+if not get_option('tests')
+    subdir_done()
+endif
+
 subproject('munit', default_options: 'werror=false')
 
 munit = dependency('munit', fallback: ['munit', 'munit_dep'])