package/nfs-utils: add optional support for libcap

When libcap was compiled before, nfs-utils will use it as optional
dependency:

$ output/host/usr/bin/x86_64-linux-readelf -a output/target/usr/sbin/sm-notify | grep NEEDED
 0x0000000000000001 (NEEDED)             Shared library: [libcap.so.2]
 0x0000000000000001 (NEEDED)             Shared library: [libtirpc.so.3]
 0x0000000000000001 (NEEDED)             Shared library: [libpthread.so.1]
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.1]

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/nfs-utils/nfs-utils.mk

@@ -28,6 +28,13 @@ NFS_UTILS_TARGETS_$(BR2_PACKAGE_NFS_UTILS_RPCDEBUG) += usr/sbin/rpcdebug
 NFS_UTILS_TARGETS_$(BR2_PACKAGE_NFS_UTILS_RPC_LOCKD) += usr/sbin/rpc.lockd
 NFS_UTILS_TARGETS_$(BR2_PACKAGE_NFS_UTILS_RPC_RQUOTAD) += usr/sbin/rpc.rquotad
 
+ifeq ($(BR2_PACKAGE_LIBCAP),y)
+NFS_UTILS_CONF_OPTS += --enable-caps
+NFS_UTILS_DEPENDENCIES += libcap
+else
+NFS_UTILS_CONF_OPTS += --disable-caps
+endif
+
 ifeq ($(BR2_PACKAGE_LIBTIRPC),y)
 NFS_UTILS_CONF_OPTS += --enable-tirpc
 NFS_UTILS_DEPENDENCIES += libtirpc