gettext: Remove spurious-looking dependencies on libxml2-native

gettext: Remove spurious-looking dependencies on libxml2-native

These were added in aae5021101224344a2b1a3af5becf74291fbbfe5, ostensibly to resolve
some sort of "host contamination" issue.  However, that commit contains no information
about what contamination was being observed or how the dependencies help.

gettext-native is being configured --with-included-libxml so it shouldn't be using
libxml2 from either the host or the sysroot, in which case the dependency would seem
to be useless.  Using the included copy of libxml2 is in any case preferable to adding
a dependency on libxml2-native because the latter brings quite a large stack of other
dependencies with it.

(From OE-Core rev: 132d329638ae32b98c36b9498c470cf0ffdcedb3)

Signed-off-by: Phil Blundell <pb@pbcl.net>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>