meson: Add toggle for glx-direct

GNU Hurd needs to turn off glx-direct, rather than special case it,
we'll just add a toggle.

CC: 18.3 <mesa-stable@lists.freedesktop.org>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>

meson.build

@@ -51,6 +51,7 @@ with_valgrind = get_option('valgrind')
 with_libunwind = get_option('libunwind')
 with_asm = get_option('asm')
 with_glx_read_only_text = get_option('glx-read-only-text')
+with_glx_direct = get_option('glx-direct')
 with_osmesa = get_option('osmesa')
 with_swr_arches = get_option('swr-arches')
 with_tools = get_option('tools')
@@ -365,9 +366,6 @@ if with_glvnd
   endif
 endif
 
-# TODO: toggle for this
-with_glx_direct = true
-
 if with_vulkan_icd_dir == ''
   with_vulkan_icd_dir = join_paths(get_option('datadir'), 'vulkan/icd.d')
 endif

meson_options.txt

@@ -318,3 +318,9 @@ option(
   choices : ['auto', 'true', 'false'],
   description : 'Enable VK_EXT_acquire_xlib_display.'
 )
+option(
+  'glx-direct',
+  type : 'boolean',
+  value : true,
+  description : 'Enable direct rendering in GLX and EGL for DRI',
+)