Add feature for code coverage information instrumentation.

Fixes #396

src/tools/features/coverage-feature.jam

@@ -0,0 +1,12 @@
+# Copyright 2019 Rene Rivera
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE_1_0.txt or copy at
+# http://www.boost.org/LICENSE_1_0.txt)
+
+# What kind of coverage information to generate.
+
+import feature ;
+
+feature.feature coverage
+    : off all test profile
+    : propagated optional ;