package/rocksdb: add gflags optional dependency

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/rocksdb/rocksdb.mk

@@ -19,6 +19,13 @@ else
 ROCKSDB_CONF_OPTS += ROCKSDB_DISABLE_BZ2=1
 endif
 
+ifeq ($(BR2_PACKAGE_GFLAGS),y)
+ROCKSDB_DEPENDENCIES += gflags
+ROCKSDB_MAKE_OPTS += ROCKSDB_DISABLE_GFLAGS=0
+else
+ROCKSDB_MAKE_OPTS += ROCKSDB_DISABLE_GFLAGS=1
+endif
+
 ifeq ($(BR2_PACKAGE_JEMALLOC),y)
 ROCKSDB_DEPENDENCIES += jemalloc
 ROCKSDB_MAKE_OPTS += ROCKSDB_DISABLE_JEMALLOC=0