Move the mainline SDK definition to system/libartpalette. am: 724d27147f am: 7cabb20ff5 am: e2abb2aacb

Original change: https://android-review.googlesource.com/c/platform/system/libartpalette/+/1382579

Change-Id: Ic930b1ac28219987fcda3ff3ea313067011e3d73