Reduce the size of boot animaion assets.

This is achieved by applying pngcrush -brute and results in a decrease
in system image size.

Bug: 28215770
Change-Id: Ib26ef54302970348d2dd3ee51fefc8ea05c578ba
diff --git a/core/res/assets/images/android-logo-mask.png b/core/res/assets/images/android-logo-mask.png
index ad40645..5512c0ad 100644
--- a/core/res/assets/images/android-logo-mask.png
+++ b/core/res/assets/images/android-logo-mask.png
Binary files differ
diff --git a/core/res/assets/images/android-logo-shine.png b/core/res/assets/images/android-logo-shine.png
index cb65f22..c5d1263 100644
--- a/core/res/assets/images/android-logo-shine.png
+++ b/core/res/assets/images/android-logo-shine.png
Binary files differ
diff --git a/core/res/assets/images/clock64.png b/core/res/assets/images/clock64.png
index 493a1ea..2e01e38f 100644
--- a/core/res/assets/images/clock64.png
+++ b/core/res/assets/images/clock64.png
Binary files differ