shell-and-utilities: add bc.

We accidentally dropped this when it moved out of toybox.

Test: treehugger
Change-Id: I7bc0fc2d3fe3822232531465d2c13d306381c4ef
diff --git a/shell_and_utilities/Android.bp b/shell_and_utilities/Android.bp
index ec4f6ab..b5a5fb6 100644
--- a/shell_and_utilities/Android.bp
+++ b/shell_and_utilities/Android.bp
@@ -12,6 +12,7 @@
     required: [
         "auditctl",
         "awk",
+        "bc",
         "bzip2",
         "ldd",
         "logwrapper",