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/BUILD b/tools/BUILD
index bab0b6e..3f3d4b2 100644
--- a/tools/BUILD
+++ b/tools/BUILD
@@ -1,51 +1,71 @@
-package(default_visibility = ['//visibility:public'])
+package(default_visibility = ["//visibility:public"])
 
-exports_files(['test_sharding_compliant'])
+exports_files(["test_sharding_compliant"])
 
 # Don't use these directly! Use //tools/build_rules/*.bzl instead.
 config_setting(
-  name = 'compiler_clang',
-  values = {'compiler': 'clang'}
+    name = "compiler_clang",
+    values = {"compiler": "clang"},
 )
+
 config_setting(
-  name = 'compiler_gcc',
-  values = {'compiler': 'gcc'}
+    name = "compiler_gcc",
+    values = {"compiler": "gcc"},
 )
+
 config_setting(
-  name = 'cpu_k8',
-  values = {'cpu': 'k8'},
+    name = "cpu_k8",
+    values = {"cpu": "k8"},
 )
+
 config_setting(
-  name = 'cpu_roborio',
-  values = {'cpu': 'roborio'},
+    name = "cpu_roborio",
+    values = {"cpu": "roborio"},
 )
+
 config_setting(
-  name = 'cpu_cortex_m4f',
-  values = {'cpu': 'cortex-m4f'},
+    name = "cpu_cortex_m4f",
+    values = {"cpu": "cortex-m4f"},
 )
+
 config_setting(
-  name = 'cpu_armhf',
-  values = {'cpu': 'armhf-debian'},
+    name = "cpu_armhf",
+    values = {"cpu": "armhf-debian"},
 )
+
 config_setting(
-  name = 'has_asan',
-  values = {'define': 'have_asan=true'},
+    name = "has_asan",
+    values = {"define": "have_asan=true"},
 )
+
 config_setting(
-  name = 'has_tsan',
-  values = {'define': 'have_tsan=true'},
+    name = "has_tsan",
+    values = {"define": "have_tsan=true"},
 )
+
 config_setting(
-  name = 'has_ubsan',
-  values = {'define': 'have_ubsan=true'},
+    name = "has_ubsan",
+    values = {"define": "have_ubsan=true"},
 )
 
 environment(name = "k8")
+
 environment(name = "armhf-debian")
+
 environment(name = "roborio")
+
 environment(name = "cortex-m4f")
+
 environment_group(
     name = "cpus",
-    environments = [":k8", ":roborio", ":armhf-debian", ":cortex-m4f"],
-    defaults = [":k8", ":roborio", ":armhf-debian"],
+    defaults = [
+        ":k8",
+        ":roborio",
+    ],
+    environments = [
+        ":k8",
+        ":roborio",
+        ":armhf-debian",
+        ":cortex-m4f",
+    ],
 )