Build fixes for fnl/musl

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 8584b07bc77ca1279bfb0666243632e0425e6254..57b7a53135a5a6afa333248e7650580b5245566f 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -19,14 +19,15 @@ group("default") {
     "//shell",
   ]
 
-  if (is_linux) {
+  # TODO(cstout): fix sandbox build for fnl/musl
+  if (is_linux && !is_fnl) {
     deps += [
       "//sandbox/linux:sandbox",
       "//sandbox/linux:sandbox_linux_unittests",
     ]
-    if (!use_ozone) {
-      deps += [ "//tools/xdisplaycheck" ]
-    }
+  }
+  if (is_linux && !use_ozone) {
+    deps += [ "//tools/xdisplaycheck" ]
   }
 
   if (is_linux || is_android) {