Update GYP for linux Vulkan to support SDK 1.0.13

gyp/gpu.gyp

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 # GYP for building gpu
 {
   'target_defaults': {
     'conditions': [
       ['skia_os != "win"', {
         'sources/': [ ['exclude', '_win.(h|cpp)$'],
@@ skipping 189 matching lines @@
                   }, {
                     'library_dirs': [ '<(vulkan_sdk_path)/Bin', ],
                   }],
                 ]
               },
             }, {
               'variables': {
                 'vulkan_lib_name': '-lvulkan',
               },
             }],
+            [ 'skia_os == "linux"', {
+              'variables': {
+                'vulkan_sdk_path' : '<!(echo $VULKAN_SDK)',
+              },
+              'include_dirs': [
+                '<(vulkan_sdk_path)/include',
+              ],
+              'direct_dependent_settings': {
+                'include_dirs': [
+                  '<(vulkan_sdk_path)/include',
+                ],
+              },
+              'link_settings': {
+                'library_dirs': [ '<(vulkan_sdk_path)/lib', ],
+              },
+            }],
           ],
           'dependencies': [
             'shaderc.gyp:shaderc_combined',
           ],
           'include_dirs': [
             '../third_party/externals/shaderc2/libshaderc/include',
           ],
           'direct_dependent_settings': {
             'include_dirs': [
               '../third_party/externals/shaderc2/libshaderc/include',
             ],
           },
           'link_settings': {
             'libraries': [ '<(vulkan_lib_name)', ],
           },
         }, {
           'sources!': [
             '<@(skgpu_vk_sources)',
           ],
         }],
       ],
     },
   ],
 }