Remove Windows-related GN build configuration

build/secondary/third_party/libjpeg_turbo/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Do not use the targets in this file unless you need a certain libjpeg
 # implementation. Use the meta target //third_party:jpeg instead.
 
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
@@ skipping 55 matching lines @@
         "simd/jfss2int-64.asm",
         "simd/jfsseflt-64.asm",
         "simd/jiss2flt-64.asm",
         "simd/jiss2fst-64.asm",
         "simd/jiss2int-64.asm",
         "simd/jiss2red-64.asm",
       ]
       defines += [ "__x86_64__" ]
     }
 
-    if (is_win) {
-      defines += [ "MSVC" ]
-      include_dirs = [ "win" ]
-      if (current_cpu == "x86") {
-        defines += [ "WIN32" ]
-      } else {
-        defines += [ "WIN64" ]
-      }
-    } else if (is_mac) {
+    if (is_mac) {
       defines += [ "MACHO" ]
       include_dirs = [ "mac" ]
     } else if (is_linux || is_android) {
       defines += [ "ELF" ]
       include_dirs = [ "linux" ]
     }
   }
 }
 
 source_set("simd") {
   if (current_cpu == "x86") {
     deps = [
       ":simd_asm",
     ]
     sources = [
       "simd/jsimd_i386.c",
     ]
-    if (is_win) {
-      cflags = [ "/wd4245" ]
-    }
   } else if (current_cpu == "x64") {
     deps = [
       ":simd_asm",
     ]
     sources = [
       "simd/jsimd_x86_64.c",
     ]
   } else if (current_cpu == "arm" && arm_version >= 7 &&
              (arm_use_neon || arm_optionally_use_neon)) {
     sources = [
@@ skipping 87 matching lines @@
   if (is_msan || is_linux) {
     sources += [ "jsimd_none.c" ]
   } else {
     deps = [
       ":simd",
     ]
   }
 
   # TODO(GYP): Compile the .asm files with YASM as GYP does.
 }