handle/copyable: Implement copyable handle

This is a generic handle type that holds a resource and uses RAII to
call a user defined function when the resource is copied or destroyed.

Tested:
    Built and run through unit tests.

Change-Id: I3d23544b2e7c8d8c6686effc03b3b7433ea18bf5
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/meson.build b/src/meson.build
index 6b1fea9..a6ff714 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -20,5 +20,6 @@
   subdir: 'stdplus')
 
 install_headers(
+  'stdplus/handle/copyable.hpp',
   'stdplus/handle/managed.hpp',
   subdir: 'stdplus/handle')