Roll arm64 sysroot

This CL is a followup to [1] which added new packges to the arm64
sysroot.  However, it did not include the changes from [2] (since it
was done on a separate branch).  This CL rolls the arm sysroot again
to get both changes.

[1] https://chromium.googlesource.com/chromium/src/+/ea2ad20b708c3946995000dd4d0fa0f8ca2e2e0e
[2] https://chromium.googlesource.com/chromium/src/+/72f0a9302524579a14a6625fc30cf8377fc197e8

BUG=webrtc:8540
TBR=thestig@chromium.org
CC=oprypin@chromium.org
NOTRY=true

Change-Id: Ie70e5145732cd6efd7fea7d9b8d3e118ea957306
Reviewed-on: https://chromium-review.googlesource.com/776030Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517355}

build/linux/sysroot_scripts/sysroots.json

@@ -12,8 +12,8 @@
         "Tarball": "debian_stretch_arm_sysroot.tar.xz"
     },
     "stretch_arm64": {
-        "Revision": "f5b4828fe6550e64f2b09951d07d93a1b9d17c5a",
-        "Sha1Sum": "5c1ae57960b399ac191511715321a26b436f8d0b",
+        "Revision": "1e9c6777efb621794e8385ab9b4faf3546c29bf2",
+        "Sha1Sum": "35fd438e9dfc39d75d1e03badc8b309e3ad94acd",
         "SysrootDir": "debian_stretch_arm64-sysroot",
         "Tarball": "debian_stretch_arm64_sysroot.tar.xz"
     },