[Tizen] Temporarily disable Vulkan backend for Linux

Author: swift-kim

impeller/tools/impeller.gni

@@ -15,7 +15,7 @@ declare_args() {
   impeller_enable_opengles = is_linux || is_win || is_android
 
   # Whether the Vulkan backend is enabled.
-  impeller_enable_vulkan = is_linux || is_win || is_android
+  impeller_enable_vulkan = is_win || is_android
 
   # Whether to use a prebuilt impellerc.
   # If this is the empty string, impellerc will be built.

tools/gn

@@ -435,7 +435,7 @@ def to_gn_args(args):
   # Enable Vulkan on all platforms except for iOS. This is just
   # to save on mobile binary size, as there's no reason the Vulkan embedder
   # features can't work on these platforms.
-  if gn_args['target_os'] not in ['ios', 'mac']:
+  if gn_args['target_os'] not in ['ios', 'mac', 'linux']:
     gn_args['skia_use_vulkan'] = True
     gn_args['skia_use_vma'] = False
     gn_args['shell_enable_vulkan'] = True