meson: add convenience variable for anv_extensions.py depdendency

Signed-off-by: Dylan Baker <dylan.c.baker@intel.com>
Reviewed-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>

src/intel/vulkan/meson.build

@@ -18,6 +18,8 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 
+anv_extensions_py = files('anv_extensions.py')
+
 anv_entrypoints = custom_target(
   'anv_entrypoints.[ch]',
   input : ['anv_entrypoints_gen.py', vk_api_xml, vk_android_native_buffer_xml],
@@ -26,7 +28,7 @@ anv_entrypoints = custom_target(
     prog_python2, '@INPUT0@', '--xml', '@INPUT1@', '--xml', '@INPUT2@',
     '--outdir', meson.current_build_dir(),
   ],
-  depend_files : files('anv_extensions.py'),
+  depend_files : anv_extensions_py,
 )
 
 anv_extensions_c = custom_target(
@@ -37,7 +39,7 @@ anv_extensions_c = custom_target(
     prog_python2, '@INPUT0@', '--xml', '@INPUT1@', '--xml', '@INPUT2@',
     '--out-c', '@OUTPUT@',
   ],
-  depend_files : files('anv_extensions.py'),
+  depend_files : anv_extensions_py,
 )
 
 anv_extensions_h = custom_target(
@@ -48,7 +50,7 @@ anv_extensions_h = custom_target(
     prog_python2, '@INPUT0@', '--xml', '@INPUT1@', '--xml', '@INPUT2@',
     '--out-h', '@OUTPUT@',
   ],
-  depend_files : files('anv_extensions.py'),
+  depend_files : anv_extensions_py,
 )
 
 intel_icd = custom_target(
@@ -60,7 +62,7 @@ intel_icd = custom_target(
     '--lib-path', join_paths(get_option('prefix'), get_option('libdir')),
     '--out', '@OUTPUT@',
   ],
-  depend_files : files('anv_extensions.py'),
+  depend_files : anv_extensions_py,
   build_by_default : true,
   install_dir : with_vulkan_icd_dir,
   install : true,