Convert libexif.gyp to new clang flags after r287092.

third_party/libexif/libexif.gyp

Index: third_party/libexif/libexif.gyp
diff --git a/third_party/libexif/libexif.gyp b/third_party/libexif/libexif.gyp
index 5819b3ae8e6ca6e8011d44be03bd2518ab6a6cb9..efb17026927947de9e8a4174b0e92ff15c8c5bce 100644
--- a/third_party/libexif/libexif.gyp
+++ b/third_party/libexif/libexif.gyp
@@ -52,24 +52,16 @@
               'sources',
             ],
           },
+          'variables': {
+            'clang_warning_flags': [
+              '-Wno-enum-conversion',
+              '-Wno-switch',
+              '-Wno-format',
+              # libexif uses fabs(int) to cast to float.
+              '-Wno-absolute-value',
+            ],
+          },
           'conditions': [
-            ['clang==1', {
-              'cflags': [
-                '-Wno-enum-conversion', 
-                '-Wno-switch',
-                # libexif uses fabs(int) to cast to float.
-                '-Wno-absolute-value',
-              ],
-              'xcode_settings': {
-                'WARNING_CFLAGS': [
-                  '-Wno-enum-conversion', 
-                  '-Wno-switch',
-                  '-Wno-format',
-                  # libexif uses fabs(int) to cast to float.
-                  '-Wno-absolute-value',
-                ],
-              },
-            }],
             ['os_posix==1 and OS!="mac"', {
               'cflags!': ['-fvisibility=hidden'],
             }],