Fix gnutls autodetection when using a cross-compiler.

It is not enough to check for pkg-config gnutls.  You may be using a
cross-compiler and have gnutls available on the host but not for the target.
This patch changes the detection to try and build an application using gnutls
and whatever compiler is available.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>




git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4989 c046a42c-6fe2-441c-8c8c-71466251a162
