ANDROID: selftests/breakpoints: Ignore breakpoint_test_arm64

The aarch64/arm64 build target was added without a matching
.gitignore entry, so a build leaves breakpoint_test_arm64 showing up
as untracked.

Fixes: f43365ee17f8d ("selftests: arm64: add test for unaligned/inexact watchpoint handling")
Bug: 539895453
Change-Id: I79200fe78c3e4a69cf43fb681798ac9c490dd761
Signed-off-by: Fuad Tabba <tabba@google.com>

tools/testing/selftests/breakpoints/.gitignore

diff --git a/tools/testing/selftests/breakpoints/.gitignore b/tools/testing/selftests/breakpoints/.gitignore
index def2e97..c5fbc4a 100644
--- a/tools/testing/selftests/breakpoints/.gitignore
+++ b/tools/testing/selftests/breakpoints/.gitignore
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 breakpoint_test
+breakpoint_test_arm64
 step_after_suspend_test