Support building db_bench using buck (facebook#13004)

Summary:
Pull Request resolved: facebook#13004

The patch extends the buckifier script so it generates a target for `db_bench` as well.

Differential Revision: D62407071

TARGETS

@@ -417,6 +417,8 @@ cpp_binary_wrapper(name="ldb", srcs=["tools/ldb.cc"], deps=[":rocksdb_tools_lib"
 
 cpp_binary_wrapper(name="db_stress", srcs=["db_stress_tool/db_stress.cc"], deps=[":rocksdb_stress_lib"], extra_preprocessor_flags=[], extra_bench_libs=False)
 
+cpp_binary_wrapper(name="db_bench", srcs=["tools/db_bench.cc"], deps=[":rocksdb_tools_lib"], extra_preprocessor_flags=[], extra_bench_libs=False)
+
 cpp_binary_wrapper(name="cache_bench", srcs=["cache/cache_bench.cc"], deps=[":rocksdb_cache_bench_tools_lib"], extra_preprocessor_flags=[], extra_bench_libs=False)
 
 cpp_binary_wrapper(name="ribbon_bench", srcs=["microbench/ribbon_bench.cc"], deps=[], extra_preprocessor_flags=[], extra_bench_libs=True)

buckifier/buckify_rocksdb.py

@@ -201,6 +201,10 @@ def generate_targets(repo_path, deps_map):
     TARGETS.add_binary(
         "db_stress", ["db_stress_tool/db_stress.cc"], [":rocksdb_stress_lib"]
     )
+    # db_bench binary
+    TARGETS.add_binary(
+        "db_bench", ["tools/db_bench.cc"], [":rocksdb_tools_lib"]
+    )
     # cache_bench binary
     TARGETS.add_binary(
         "cache_bench", ["cache/cache_bench.cc"], [":rocksdb_cache_bench_tools_lib"]