Fix arm64 build

Change-Id: I62822f306ed9f5d37c890f49b3a25f1e77211526
diff --git a/BUILD.gn b/BUILD.gn
index fbb613c..af9ae11 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -58,6 +58,12 @@
     "-Wno-unused-function",
   ]
 
+  if (current_cpu == "arm64") {
+    cflags += [
+      "-Wno-unknown-attributes",
+    ]
+  }
+
   defines = [ "HAVE_CONFIG_H" ]
   include_dirs = [ target_gen_dir ]
 }
@@ -119,19 +125,28 @@
     "pixman/pixman-region16.c",
     "pixman/pixman-region32.c",
     "pixman/pixman-solid-fill.c",
-    "pixman/pixman-sse2.c",
     "pixman/pixman-timer.c",
     "pixman/pixman-trap.c",
     "pixman/pixman-utils.c",
-    "pixman/pixman-x86.c",
     "pixman/pixman.c",
   ]
 
   public_configs = [ ":pixman_config" ]
   deps = [
     ":pixman_private",
-    ":pixman_ssse3",
   ]
+
+  if (current_cpu == "x64") {
+    sources += [
+      "pixman/pixman-x86.c",
+      "pixman/pixman-sse2.c",
+    ]
+
+    deps += [
+      ":pixman_ssse3",
+    ]
+  }
+
 }
 
 source_set("pixman_ssse3") {