Remove LTO build speed workaround for libhwui

Since https://r.android.com/2856020, eng builds no longer perform costly
link time optimizations. The workaround that disables LTO build speed is
no longer necessary.

Test: presubmit
Change-Id: Ic76b7bb5866e8df4b19793aa06253910e5c5d384

libs/hwui/Android.bp

@@ -66,14 +66,6 @@ cc_defaults {
         "external/skia/src/core",
     ],
 
-    product_variables: {
-        eng: {
-            lto: {
-                never: true,
-            },
-        },
-    },
-
     target: {
         android: {
             include_dirs: [