gnutls: remove --with-libz-prefix configure option
The default search path in sysroot is sufficient to find zlib, so the
--with-libz-prefix configure option seems to be unnecessary.
For target builds, relying on sysroot also prevents an absolute path
from being hardcoded in the gnutls.pc pkg-config file.
(From OE-Core rev:
7a800bfeb6c8c83ee7cc74739f496982cd71c8e8)
Signed-off-by: Andre McCurdy <armccurdy@gmail.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
