Enable Linux shell build (#8233)

Enables building of the GLFW shell and the related unit tests.

BUILD.gn

@@ -57,6 +57,13 @@ group("flutter") {
     if (!is_win) {
       public_deps += [ "$flutter_root/shell/common:shell_benchmarks" ]
     }
+
+    if (is_linux) {
+      public_deps += [
+        "$flutter_root/shell/platform/common/cpp/client_wrapper:client_wrapper_unittests",
+        "$flutter_root/shell/platform/glfw/client_wrapper:client_wrapper_glfw_unittests",
+      ]
+    }
   }
 }
 

shell/platform/BUILD.gn

@@ -12,7 +12,9 @@ group("platform") {
       "android",
     ]
   } else if (is_linux) {
-    deps = []
+    deps = [
+      "linux",
+    ]
   } else if (is_win) {
     deps = [
       "windows",

shell/platform/linux/BUILD.gn

@@ -13,10 +13,22 @@ group("linux") {
   ]
 }
 
+# Temporary workraround for the issue describe in
+# https://github.com/flutter/flutter/issues/14509 and
+# https://github.com/flutter/flutter/issues/14438
+# Remove once the build infrastructure moves to Ubuntu 18.04 or newer, where
+# the underlying issue is fixed.
+config("disable_fatal_link_warnings") {
+  visibility = [ ":*" ]
+  ldflags = [ "-Wl,--no-fatal-warnings" ]
+}
+
 shared_library("flutter_linux") {
   deps = [
     "$flutter_root/shell/platform/glfw:flutter_glfw",
   ]
 
+  configs += [ ":disable_fatal_link_warnings" ]
+
   public_configs = [ "$flutter_root:config" ]
 }