we can move dst here

clang-tidy pointed out this opportunity in the Google3 build.

Change-Id: I2ab01602fae2d3132a229006c06625371342e18a
Reviewed-on: https://skia-review.googlesource.com/18926
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>

src/core/SkColorSpaceXformImageGenerator.cpp

@@ -35,7 +35,7 @@ SkColorSpaceXformImageGenerator::SkColorSpaceXformImageGenerator(const SkBitmap&
                                                                  sk_sp<SkColorSpace> dst)
     : INHERITED(src.info().makeColorSpace(dst), kNeedNewImageUniqueID)
     , fSrc(src)
-    , fDst(dst)
+    , fDst(std::move(dst))
 {}
 
 bool SkColorSpaceXformImageGenerator::onGetPixels(const SkImageInfo& info, void* pixels,