Define missing IMAGETYPE_ constants

Defined IMAGETYPE_UNKNOWN and IMAGETYPE_COUNT

Closes #1634
Closes #1638

Reviewed By: @ptarjan

Differential Revision: D1144855

Pulled By: @scannell

hphp/system/idl/constants.idl.json

@@ -1971,6 +1971,10 @@
             "name": "IMAGETYPE_BMP",
             "value": 6
         },
+        {
+            "name": "IMAGETYPE_COUNT",
+            "value": 18
+        },
         {
             "name": "IMAGETYPE_GIF",
             "value": 1
@@ -2027,6 +2031,10 @@
             "name": "IMAGETYPE_TIFF_MM",
             "value": 8
         },
+        {
+            "name": "IMAGETYPE_UNKNOWN",
+            "value": 0
+        },
         {
             "name": "IMAGETYPE_WBMP",
             "value": 15

hphp/test/slow/ext_image/1791.php

@@ -17,3 +17,5 @@ var_dump(image_type_to_mime_type(IMAGETYPE_IFF));
 var_dump(image_type_to_mime_type(IMAGETYPE_WBMP));
 var_dump(image_type_to_mime_type(IMAGETYPE_XBM));
 var_dump(image_type_to_mime_type(IMAGETYPE_ICO));
+var_dump(image_type_to_mime_type(IMAGETYPE_UNKNOWN));
+var_dump(image_type_to_mime_type(IMAGETYPE_COUNT));

hphp/test/slow/ext_image/1791.php.expect

@@ -15,3 +15,5 @@ string(9) "image/iff"
 string(18) "image/vnd.wap.wbmp"
 string(9) "image/xbm"
 string(24) "image/vnd.microsoft.icon"
+string(24) "application/octet-stream"
+string(24) "application/octet-stream"