Address review comments

src/build_defs.bzl

@@ -282,7 +282,6 @@ def mozc_win32_cc_prod_binary(
         executable_name_map = {},
         srcs = [],
         deps = [],
-        hdrs = [],
         linkopts = [],
         cpu = CPU.X64,
         static_crt = False,
@@ -305,7 +304,6 @@ def mozc_win32_cc_prod_binary(
       executable_name_map: a map from the branding name to the executable name.
       srcs: .cc files to build the executable.
       deps: deps to build the executable.
-      hdrs: header files to build the executable.
       linkopts: linker options to build the executable.
       cpu: optional. The target CPU architecture.
       static_crt: optional. True if the target should be built with static CRT.
@@ -405,7 +403,7 @@ register_extension_info(
 
 def _win_library_transition_impl(
         settings,  # @unused
-        attr):
+        attr):  # @unused
     return {
         "//command_line_option:features": [],
     }
@@ -490,7 +488,6 @@ def mozc_cc_win32_library(
     cc_binary_target_intermediate_name = name + "_fake"
     cc_binary_target_name = cc_binary_target_intermediate_name + ".dll"
     filegroup_target_name = name + "_lib_group"
-    cc_binary_target_libname = cc_binary_target_name + ".if.dll"
     cc_import_taget_name = name + "_import"
 
     mozc_cc_binary(