Use a Raspbian sysroot for armhf-debian builds

This has a newer libc than the linaro toolchain we were using, which is
necessary for using some prebuilt shared objects.

Change-Id: Id4bcf3b1a18300aa40c77cda60050e3987e81dd1
diff --git a/compilers/armhf_debian_rootfs.BUILD b/compilers/armhf_debian_rootfs.BUILD
new file mode 100644
index 0000000..004b82a
--- /dev/null
+++ b/compilers/armhf_debian_rootfs.BUILD
@@ -0,0 +1,15 @@
+filegroup(
+    name = "sysroot_files",
+    srcs = glob(
+        include = [
+            "include/**",
+            "lib/**",
+            "usr/include/**",
+            "usr/lib/**",
+        ],
+        exclude = [
+            "usr/share/**",
+        ],
+    ),
+    visibility = ["//visibility:public"],
+)