move vector math out of libui

created a new header-only static libmath lib

Test: built & ran
Bug: n/a
Change-Id: Ic63ef5f54d9a0de07a9ab9e4d67be01ab6169fc0
diff --git a/services/surfaceflinger/DisplayHardware/HWC2.h b/services/surfaceflinger/DisplayHardware/HWC2.h
index e129a3a..4419dc1 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2.h
+++ b/services/surfaceflinger/DisplayHardware/HWC2.h
@@ -24,7 +24,7 @@
 #undef HWC2_USE_CPP11
 
 #include <ui/HdrCapabilities.h>
-#include <ui/mat4.h>
+#include <math/mat4.h>
 
 #include <utils/Log.h>
 #include <utils/StrongPointer.h>