Change BUCK template files (#4624)

Summary:
Slightly changes the format of generated BUCK files for Facebook consumption. Generated targets end up looking like this:
```
cpp_library(
    name = "rocksdb_tools_lib",
    srcs = [
        "tools/db_bench_tool.cc",
        "tools/trace_analyzer_tool.cc",
        "util/testutil.cc",
    ],
    auto_headers = AutoHeaders.RECURSIVE_GLOB,
    arch_preprocessor_flags = rocksdb_arch_preprocessor_flags,
    compiler_flags = rocksdb_compiler_flags,
    preprocessor_flags = rocksdb_preprocessor_flags,
    deps = [":rocksdb_lib"],
    external_deps = rocksdb_external_deps,
)
```
Instead of
```
cpp_library(
    name = "rocksdb_tools_lib",
    srcs = [
        "tools/db_bench_tool.cc",
        "tools/trace_analyzer_tool.cc",
        "util/testutil.cc",
    ],
    headers = AutoHeaders.RECURSIVE_GLOB,
    arch_preprocessor_flags = rocksdb_arch_preprocessor_flags,
    compiler_flags = rocksdb_compiler_flags,
    preprocessor_flags = rocksdb_preprocessor_flags,
    deps = [":rocksdb_lib"],
    external_deps = rocksdb_external_deps,
)
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4624

Reviewed By: riversand963

Differential Revision: D12906711

Pulled By: philipjameson

fbshipit-source-id: 32ab64a3390cdcf2c4043ff77517ac1ad58a5e2b

buckifier/targets_builder.py

@@ -31,13 +31,16 @@ class TARGETSBuilder:
         self.targets_file.close()
 
     def add_library(self, name, srcs, deps=None, headers=None):
+        headers_attr_prefix = ""
         if headers is None:
+            headers_attr_prefix = "auto_"
             headers = "AutoHeaders.RECURSIVE_GLOB"
-        self.targets_file.write(targets_cfg.library_template % (
+        self.targets_file.write(targets_cfg.library_template.format(
-            name,
+            name=name,
-            pretty_list(srcs),
+            srcs=pretty_list(srcs),
-            headers,
+            headers_attr_prefix=headers_attr_prefix,
-            pretty_list(deps)))
+            headers=headers,
+            deps=pretty_list(deps)))
         self.total_lib = self.total_lib + 1
 
     def add_binary(self, name, srcs, deps=None):

buckifier/targets_cfg.py

@@ -85,13 +85,13 @@ if default_allocator.startswith("jemalloc") and sanitizer == "":
 
 library_template = """
 cpp_library(
-    name = "%s",
+    name = "{name}",
-    srcs = [%s],
+    srcs = [{srcs}],
-    headers = %s,
+    {headers_attr_prefix}headers = {headers},
     arch_preprocessor_flags = rocksdb_arch_preprocessor_flags,
     compiler_flags = rocksdb_compiler_flags,
     preprocessor_flags = rocksdb_preprocessor_flags,
-    deps = [%s],
+    deps = [{deps}],
     external_deps = rocksdb_external_deps,
 )
 """