Use the downloaded clang when building for armhf-debian

This makes it work on a barebones Stretch installation.

Also add building for this CPU to the CI script so we know it keeps
working, which means marking everything that's supposed to work
appropriately.

Change-Id: Ic050ce20eae45c6b23e0e42dddb24db3ebc70b84
diff --git a/tools/cpp/BUILD b/tools/cpp/BUILD
index e5cdcc7..afa296d 100644
--- a/tools/cpp/BUILD
+++ b/tools/cpp/BUILD
@@ -158,6 +158,7 @@
 filegroup(
     name = "linaro-gcc-files",
     srcs = [
+        ":clang_3p6_all_files",
         "//tools/cpp/linaro_linux_gcc:clang-symlinks",
         "//tools/cpp/linaro_linux_gcc:tool-wrappers",
         "@linaro_linux_gcc_4_9_repo//:compiler_pieces",
@@ -167,6 +168,7 @@
 filegroup(
     name = "linaro_linux_linker_files",
     srcs = [
+        ":clang_3p6_linker_files",
         "//tools/cpp/linaro_linux_gcc:ar",
         "//tools/cpp/linaro_linux_gcc:clang",
         "//tools/cpp/linaro_linux_gcc:clang-ld",
@@ -180,10 +182,20 @@
 filegroup(
     name = "linaro_linux_compiler_files",
     srcs = [
+        ":clang_3p6_compiler_files",
         "//tools/cpp/linaro_linux_gcc:as",
         "//tools/cpp/linaro_linux_gcc:clang",
         "//tools/cpp/linaro_linux_gcc:gcc",
         "//tools/cpp/linaro_linux_gcc:ld",
+        "@linaro_linux_gcc_4_9_repo//:compiler_pieces",
+    ],
+)
+
+filegroup(
+    name = "linaro_linux_strip_files",
+    srcs = [
+        "//tools/cpp/linaro_linux_gcc:strip",
+        "@linaro_linux_gcc_4_9_repo//:compiler_pieces",
     ],
 )
 
@@ -197,7 +209,7 @@
     linker_files = ":linaro_linux_linker_files",
     objcopy_files = "//tools/cpp/linaro_linux_gcc:objcopy",
     static_runtime_libs = [":empty"],
-    strip_files = "//tools/cpp/linaro_linux_gcc:strip",
+    strip_files = ":linaro_linux_strip_files",
     supports_param_files = 1,
 )