Get all our roborio tools loading downloaded .sos

This is the last piece to make `bazel build --cpu=roborio //...` work on
a barebones Stretch system.

Change-Id: I87b8737ee479dd16c9421f81a42c5ecf6413f822
diff --git a/tools/cpp/BUILD b/tools/cpp/BUILD
index 3bee68e..e5cdcc7 100644
--- a/tools/cpp/BUILD
+++ b/tools/cpp/BUILD
@@ -133,6 +133,14 @@
     ],
 )
 
+filegroup(
+    name = "roborio_strip_files",
+    srcs = [
+        "//tools/cpp/arm-frc-linux-gnueabi:strip",
+        "@arm_frc_linux_gnueabi_repo//:compiler_pieces",
+    ],
+)
+
 cc_toolchain(
     name = "cc-compiler-roborio",
     all_files = ":roborio-compiler-files",
@@ -143,7 +151,7 @@
     linker_files = ":roborio_linker_files",
     objcopy_files = "//tools/cpp/arm-frc-linux-gnueabi:objcopy",
     static_runtime_libs = [":empty"],
-    strip_files = "//tools/cpp/arm-frc-linux-gnueabi:strip",
+    strip_files = ":roborio_strip_files",
     supports_param_files = 1,
 )