Embed bytecode in C object when using -custom

Embed bytecode in C object when using -custom

This patch fixes non-strippability of bytecode executables linked with
custom runtime. The new behaviour is enabled when OCAML_CUSTOM_EMBED
is set to "y", or when DEB_HOST_ARCH is non-empty.

Forwarded: not-needed
Bug-Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=256900
Bug-Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=627761
Bug-Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=678577
Signed-off-by: Stephane Glondu <steph@glondu.net>
Gbp-Pq: Name 0006-Embed-bytecode-in-C-object-when-using-custom.patch