Disable swiftshader tests for FEMU

Author: bdero

shell/platform/embedder/BUILD.gn

@@ -11,8 +11,10 @@ import("//flutter/testing/testing.gni")
 
 declare_args() {
   embedder_enable_software = shell_enable_software
-  embedder_enable_vulkan = shell_enable_vulkan
-  embedder_enable_gl = shell_enable_gl
+
+  # The swiftshader unittests don't work on Fuchsia yet.
+  embedder_enable_vulkan = !is_fuchsia && shell_enable_vulkan
+  embedder_enable_gl = !is_fuchsia && shell_enable_gl
   embedder_enable_metal = shell_enable_metal
 }