samba4: update answer cache

Some toolchain/package combinations require an additional touch (answer)
in the cache file. Fixes:
http://autobuild.buildroot.net/results/426/4266a1690b85bde8da130a84845d1985128bda63/

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/samba4/samba4-cache.txt

@@ -23,6 +23,7 @@ Checking whether setreuid is available: OK
 Checking whether setresuid is available: OK
 Checking whether seteuid is available: OK
 Checking whether fcntl locking is available: OK
+Checking whether fcntl lock supports open file description locks: OK
 Checking for the maximum value of the 'time_t' type: OK
 Checking whether the realpath function allows a NULL argument: OK
 Checking whether POSIX capabilities are available: OK