create_config: remove *dir block

create_config: remove *dir block

Now only the qemu_*dir variables will become #defines. The other
directory names aren't used by the C code.

That means the following #defines won't be available in C code anymore:

 - CONFIG_QEMU_BINDIR
 - CONFIG_QEMU_LIBDIR
 - CONFIG_QEMU_INCLUDEDIR
 - CONFIG_QEMU_MANDIR
 - CONFIG_QEMU_SYSCONFDIR
 - CONFIG_QEMU_LIBEXECDIR

The following #defines are going to be kept because they are handled by
the qemu_* block on create_config:

 - CONFIG_QEMU_CONFDIR
 - CONFIG_QEMU_DATADIR
 - CONFIG_QEMU_DOCDIR

This one will be kept because it is set directly by ./configure:

 - CONFIG_QEMU_HELPERDIR

This patch keeps the 'prefix=*' (CONFIG_QEMU_PREFIX) pattern because
other variables may use $prefix on their config-host.mak definitions.
The remaining code will be simplified on a further patch.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>