Source files dependencies detection for RocksDB plugins. (#9120)

Summary:
Otherwise a rebuild is not done if a RocksDB plugin header file is
changed.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9120

Test Plan:
Build RocksDB with a plugin.
Change a header file of the RocksDB plugin and rebuild.
Signed-off-by: NDennis Maisenbacher <dennis.maisenbacher@wdc.com>

Reviewed By: riversand963

Differential Revision: D32223303

Pulled By: ajkr

fbshipit-source-id: 76d31b10fe915906edc181c7b6398a09b7d079ee

Makefile

@@ -508,6 +508,7 @@ STRESS_OBJECTS =  $(patsubst %.cc, $(OBJ_DIR)/%.o, $(STRESS_LIB_SOURCES))
 ALL_SOURCES  = $(filter-out util/build_version.cc, $(LIB_SOURCES)) $(TEST_LIB_SOURCES) $(MOCK_LIB_SOURCES) $(GTEST_DIR)/gtest/gtest-all.cc
 ALL_SOURCES += $(TOOL_LIB_SOURCES) $(BENCH_LIB_SOURCES) $(CACHE_BENCH_LIB_SOURCES) $(ANALYZER_LIB_SOURCES) $(STRESS_LIB_SOURCES)
 ALL_SOURCES += $(TEST_MAIN_SOURCES) $(TOOL_MAIN_SOURCES) $(BENCH_MAIN_SOURCES)
+ALL_SOURCES += $(ROCKSDB_PLUGIN_SOURCES)
 
 TESTS = $(patsubst %.cc, %, $(notdir $(TEST_MAIN_SOURCES)))
 TESTS += $(patsubst %.c, %, $(notdir $(TEST_MAIN_SOURCES_C)))