build: Add glib_debug option

To allow disabling debug infrastructure in builds with debug symbols.

docs/macros.txt

@@ -5,6 +5,10 @@ GLib's configure options and corresponding macros
 	none
 --buildtype={debug,debugoptimized}	[debugoptimized is the default]
 	-DG_ENABLE_DEBUG -g
+-Dglib_debug=disabled
+	Omits G_ENABLE_DEBUG when implied by --buildtype/-Ddebug
+-Dglib_debug=enabled
+	Defines G_ENABLE_DEBUG regardless of --buildtype/-Ddebug
 -Dglib_asserts=false
 	-DG_DISABLE_ASSERT
 -Dglib_checks=false

meson.build

@@ -235,7 +235,8 @@ endif
 # Use debug/optimization flags to determine whether to enable debug or disable
 # cast checks
 glib_debug_cflags = []
-if get_option('debug')
+glib_debug = get_option('glib_debug')
+if glib_debug.enabled() or (glib_debug.auto() and get_option('debug'))
   glib_debug_cflags += ['-DG_ENABLE_DEBUG']
   message('Enabling various debug infrastructure')
 elif get_option('optimization') in ['2', '3', 's']

meson_options.txt

@@ -105,6 +105,12 @@ option('oss_fuzz',
        value : 'disabled',
        description : 'Indicate oss-fuzz build environment')
 
+option('glib_debug',
+       type : 'feature',
+       value : 'auto',
+       yield : true,
+       description : 'Enable GLib debug infrastructure (see docs/macros.txt)')
+
 option('glib_assert',
        type : 'boolean',
        value : true,