package/libvncserver: correct WITH_THREADS=ON/OFF logic

Commit ee59023794f5540e5 (package/libvncserver: bump to version 0.9.12)
changes the package from autotools to cmake and accidently inverted the
threads logic.

The reason this was not noticed is that the build system verifies if threads
support works and otherwise disables it even when -DWITH_THREADS=ON is
passed, E.G.  for a nothread configuration:

cmake ... -DWITH_THREADS=ON ...
..
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - not found

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/libvncserver/libvncserver.mk

@@ -22,7 +22,7 @@ LIBVNCSERVER_CONF_OPTS += \
 	-DWITH_SDL=OFF \
 	-DWITH_TESTS=OFF
 
-ifneq ($(BR2_TOOLCHAIN_HAS_THREADS),y)
+ifeq ($(BR2_TOOLCHAIN_HAS_THREADS),y)
 LIBVNCSERVER_CONF_OPTS += -DWITH_THREADS=ON
 else
 LIBVNCSERVER_CONF_OPTS += -DWITH_THREADS=OFF