remove unneeded skia flag for encoding api

Bug: 
Change-Id: I8cef060ee121c90f5ad405dd55a5ddb79676d9f2
Reviewed-on: https://chromium-review.googlesource.com/569990Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486424}

skia/config/SkUserConfig.h

@@ -202,10 +202,6 @@ SK_API void SkDebugf_FileLine(const char* file, int line, bool fatal,
 #   define SK_SUPPORT_LEGACY_ANISOTROPIC_MIPMAP_SCALE
 #endif
 
-#ifndef SK_SUPPORT_LEGACY_IMAGE_ENCODE_API
-#define SK_SUPPORT_LEGACY_IMAGE_ENCODE_API
-#endif
-
 // Remove this after we fixed all the issues related to the new SDF algorithm
 // (https://codereview.chromium.org/1643143002)
 #ifndef    SK_USE_LEGACY_DISTANCE_FIELDS