tree e873a1dde00e692b6b14b146fc263aba5490d264
parent 9b683e1fb65325a32b0a7fe11ea280fa5a1e8eda
author Colin Cross <ccross@android.com> 1469662085 -0700
committer Dan Willemsen <dwillemsen@google.com> 1472840124 -0700

Fix build

In make, appending to a non-existant variable using += results in
delayed evalution of the RHS.  If another Android.mk file assigns to GEN
between this one and when ALL_COPIED_HEADERS is evaluated, it will see
the new value of GEN.

Replace += with :=.

Change-Id: I77400bf7eed788cae89dcd9fd690717db4780f39
(cherry picked from commit d07e32b114801d8631696fd7e88649b5e36ccae5)