Add support for CR3s with embedded heif thumbnails

Change-Id: I2cb6b1e46ed91961744cc5b795cc7144c6cacb54
diff --git a/piex.gyp b/piex.gyp
index 737a0c2..15741dc 100755
--- a/piex.gyp
+++ b/piex.gyp
@@ -18,11 +18,13 @@
   'type': 'static_library',
   'sources': [
     'src/piex.cc',
+    'src/piex_cr3.cc',
     'src/tiff_parser.cc',
   ],
   'variables': {
     'headers': [
       'src/piex.h',
+      'src/piex_cr3.h',
       'src/piex_types.h',
       'src/tiff_parser.h',
     ],