clean up use of register storage class

BUILD.gn

 # Copyright 2016 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 declare_args() {
   skia_enable_tools = !is_fuchsia && !is_component_build
 
   skia_use_expat = true
   skia_use_fontconfig = is_linux
@@ skipping 204 matching lines @@
 
 opts("avx") {
   enabled = is_x86
   sources = opts_gypi.avx_sources
   cflags = [ "-mavx" ]
 }
 
 opts("dsp") {
   enabled = current_cpu == "mipsel"
   sources = opts_gypi.mips_dsp_sources
-  cflags = [ "-Wno-deprecated-register" ]  # FIXME
+  cflags = []
 }
 
 # Any feature of Skia that requires third-party code should be optional and use this template.
 template("optional") {
   if (invoker.enabled) {
     config(target_name + "_public") {
       defines = invoker.public_defines
     }
     source_set(target_name) {
       forward_variables_from(invoker, "*", [ "public_defines" ])
@@ skipping 575 matching lines @@
         "tools/using_skia_and_harfbuzz.cpp",
       ]
       deps = [
         ":skia",
         "//third_party/harfbuzz",
       ]
       testonly = true
     }
   }
 }