Add libjpeg-turbo library (depends on yasm)
Mangle external function names to avoid conflict with libjpeg
Take advantage of direct color conversion (RGBA, BGRA, 565)
Prepare to use jpeg_skip_scanlines (when it is upstreamed)

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/b60c3f8291529303299262dba19b1a896060bd2d

Committed: https://skia.googlesource.com/skia/+/f8bf9181d7b0463c8e371755cfbb9ece90b34fc5

Committed: https://skia.googlesource.com/skia/+/e9e3ee33f30c14c31afd5fc3fe4dda7f15783c75

Committed: https://skia.googlesource.com/skia/+/40141b57f061fbfcc2fa38da942d9efe25aca4d0

Review URL: https://codereview.chromium.org/1180983002
diff --git a/dm/DM.cpp b/dm/DM.cpp
index 40823c4..c3a4272 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -208,7 +208,7 @@
     // TODO (msarett): Add more scaling tests as we implement more flexible scaling.
     // TODO (msarett): Implement scaling tests for SkImageDecoder in order to compare with these
     //                 tests.  SkImageDecoder supports downscales by integer factors.
-    const float scales[] = { 0.125f, 0.25f, 0.5f, 1.0f };
+    const float scales[] = { 0.125f, 0.25f, 0.375f, 0.5f, 0.625f, 0.750f, 0.875f, 1.0f };
 
     for (float scale : scales) {
         // Build additional test cases for images that decode natively to non-canvas types