package/libcurl: fix configure options for GnuTLS

Buildroot commit fb5fb06ee5a886df5036c5c5e6c4536f2bc8e1c1 bumped libcurl
to 8.16.0 which includes commit
https://github.com/curl/curl/commit/2f6524ce3c3a8231c62d1e0c8af509fe5b0228a0
to limit the use of the configure option --with-ca-fallback to OpenSSL
causing build errors with GnuTLS:

configure: error: --with-ca-fallback only works with OpenSSL

Fixes: https://autobuild.buildroot.net/results/64f/64fad87dddecda1e8ff6b0a9abc0b827b5136e4f/

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Reviewed-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Julien Olivain <ju.o@free.fr>

package/libcurl/libcurl.mk

@@ -68,8 +68,7 @@ LIBCURL_CONF_OPTS += --without-openssl
 endif
 
 ifeq ($(BR2_PACKAGE_LIBCURL_GNUTLS),y)
-LIBCURL_CONF_OPTS += --with-gnutls=$(STAGING_DIR)/usr \
-	--with-ca-fallback
+LIBCURL_CONF_OPTS += --with-gnutls=$(STAGING_DIR)/usr
 LIBCURL_DEPENDENCIES += gnutls
 else
 LIBCURL_CONF_OPTS += --without-gnutls