cmake looks at all include statements, even if they're not used. To make
builds deterministic and avoid needing to add binutils as a dependency
for libzypp, completely remove the include from the header file, even if
it is never used.

This avoids issues where you'd build binutils, then libzypp, then remove
binutils (and hence ansidecl.h) and then recompile libzypp which would
still have the dependency and hence fail.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>