Build and upload Debian Stretch sysroots

BUG=751812
R=thestig@chromium.org

Change-Id: Ied009e9839bffced122137616b6bc3bcc7b337f0
Reviewed-on: https://chromium-review.googlesource.com/598945
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491523}

build/linux/sysroot_scripts/sysroots.json

@@ -28,5 +28,35 @@
         "Sha1Sum": "67da4cf69e87719d3ca8427771c927b6af95ffba",
         "SysrootDir": "debian_jessie_mips-sysroot",
         "Tarball": "debian_jessie_mips_sysroot.tar.xz"
+    },
+    "stretch_amd64": {
+        "Revision": "7d1a17d2a858e32ce6b8a237d603019a2e3ac0b0",
+        "Sha1Sum": "4fd5bacc951f648462702952ce14063b306ce6ba",
+        "SysrootDir": "debian_stretch_amd64-sysroot",
+        "Tarball": "debian_stretch_amd64_sysroot.tar.xz"
+    },
+    "stretch_arm": {
+        "Revision": "7d1a17d2a858e32ce6b8a237d603019a2e3ac0b0",
+        "Sha1Sum": "11e30b748de602ece73687ec0bf972e662a31f3e",
+        "SysrootDir": "debian_stretch_arm-sysroot",
+        "Tarball": "debian_stretch_arm_sysroot.tar.xz"
+    },
+    "stretch_arm64": {
+        "Revision": "7d1a17d2a858e32ce6b8a237d603019a2e3ac0b0",
+        "Sha1Sum": "f863c58810c8b4e9b556ffc7fc3980f9e3ba6fc2",
+        "SysrootDir": "debian_stretch_arm64-sysroot",
+        "Tarball": "debian_stretch_arm64_sysroot.tar.xz"
+    },
+    "stretch_i386": {
+        "Revision": "7d1a17d2a858e32ce6b8a237d603019a2e3ac0b0",
+        "Sha1Sum": "32362c929300daad99c071ed80b697a618e76c79",
+        "SysrootDir": "debian_stretch_i386-sysroot",
+        "Tarball": "debian_stretch_i386_sysroot.tar.xz"
+    },
+    "stretch_mips": {
+        "Revision": "7d1a17d2a858e32ce6b8a237d603019a2e3ac0b0",
+        "Sha1Sum": "182f5c1d3347d54894ef31e273e2859d4ddc212d",
+        "SysrootDir": "debian_stretch_mips-sysroot",
+        "Tarball": "debian_stretch_mips_sysroot.tar.xz"
     }
 }