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/aos/common/logging/BUILD b/aos/common/logging/BUILD
index 6d0d956..09e355d 100644
--- a/aos/common/logging/BUILD
+++ b/aos/common/logging/BUILD
@@ -10,6 +10,9 @@
         "interface.h",
         "logging.h",
     ],
+    compatible_with = [
+        "//tools:armhf-debian",
+    ],
     visibility = ["//visibility:public"],
     deps = [
         ":sizes",
@@ -106,6 +109,9 @@
     hdrs = [
         "sizes.h",
     ],
+    compatible_with = [
+        "//tools:armhf-debian",
+    ],
 )
 
 cc_test(
@@ -128,6 +134,9 @@
     hdrs = [
         "queue_logging.h",
     ],
+    compatible_with = [
+        "//tools:armhf-debian",
+    ],
     visibility = ["//visibility:public"],
     deps = [
         ":logging",
@@ -161,6 +170,9 @@
     hdrs = [
         "printf_formats.h",
     ],
+    compatible_with = [
+        "//tools:armhf-debian",
+    ],
     visibility = ["//visibility:public"],
     deps = [
         "//aos/common:macros",
@@ -175,6 +187,9 @@
     hdrs = [
         "implementations.h",
     ],
+    compatible_with = [
+        "//tools:armhf-debian",
+    ],
     linkopts = [
         "-lpthread",
     ],