autotools.bbclass: Don't copy into non-existant directory
* If configure.ac contains AM_GNU_GETTEXT and po/Makefile.in.in
doesn't exist, autotools_do_configure() copies a local
version of Makefile.in.in to this location. If the directory
'po' doesn't exist, the function aborts.
* This patch verifies that the directory exists before copying
a file to it. This fixes libcddb, which uses AM_GNU_GETTEXT,
but has no 'po' directory.
Signed-off-by: Andreas Oberritter <obi@opendreambox.org>
