Remove /utf-8 flag added in #14197

We have received several reports in #17036 that the addition of this flag
actually broke the use of command argument files with non-ASCII characters in
their names. It looks like #14253 ended up fixing the original issue with a
different solution anyway. Hopefully this change fixes the issue with non-ASCII
characters.

PiperOrigin-RevId: 655660885

Author: acozzette

build_defs/cpp_opts.bzl

@@ -15,7 +15,6 @@ COPTS = select({
         "/wd4506",  # no definition for inline function 'function'
         "/wd4800",  # 'type' : forcing value to bool 'true' or 'false' (performance warning)
         "/wd4996",  # The compiler encountered a deprecated declaration.
-        "/utf-8",  # Set source and execution character sets to UTF-8
     ],
     "//conditions:default": [
         "-DHAVE_ZLIB",