gallium: Add option to not add version to libgallium filename

This is unneeded in some environments, like ChromeOS and Android.  And
for CrOS it specifically causes problems with the gpu sandbox rules.. we
don't want to have to update the sandbox rules for each new mesa
version.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30579>

meson_options.txt

@@ -65,6 +65,14 @@ option(
   description : 'Location to install dri drivers. Default: $libdir/dri.'
 )
 
+option(
+  'unversion-libgallium',
+  type : 'boolean',
+  value : false,
+  description : 'Do not include mesa version in libgallium DSO filename. ' +
+                'Do not enable unless you know what you are doing. Default: false'
+)
+
 option(
   'dri-search-path',
   type : 'string',

src/gallium/targets/dri/meson.build

@@ -22,8 +22,14 @@ if with_ld_dynamic_list
   gallium_dri_link_depends += files('../dri.dyn')
 endif
 
+if get_option('unversion-libgallium')
+  libgallium_name = 'gallium_dri'
+else
+  libgallium_name = 'gallium-@0@'.format(meson.project_version())
+endif
+
 libgallium_dri = shared_library(
-  'gallium-@0@'.format(meson.project_version()),
+  libgallium_name,
   files('dri_target.c'),
   include_directories : [
     inc_include, inc_src, inc_mapi, inc_mesa, inc_gallium, inc_gallium_aux, inc_util, inc_gallium_drivers,