Bazel client, Windows: support /dev/null

Support passing /dev/null and NUL as flag values
for flags like --bazelrc.

In particular, special-case these paths in
methods like blaze_util::ReadFile,
blaze_util::IsDirectory, etc.

Fixes https://github.com/bazelbuild/bazel/issues/2354

RELNOTES[NEW]: Windows: "/dev/null" is now a supported path, e.g. --bazelrc=/dev/null now works

--
PiperOrigin-RevId: 144195994
MOS_MIGRATED_REVID=144195994

1 files changed, 2 insertions, 0 deletions

diff --git a/src/main/cpp/util/strings.h b/src/main/cpp/util/strings.h
index 66502266bf..61187b73cb 100644
--- a/src/main/cpp/util/strings.h
+++ b/src/main/cpp/util/strings.h
@@ -106,6 +106,8 @@ void StringPrintf(std::string *str, const char *format, ...);
 // Convert str to lower case. No locale handling, this is just for ASCII.
 void ToLower(std::string *str);
 
+std::string AsLower(const std::string &str);
+
 // Convert a wchar_t string to a char string. Useful when consuming results of
 // widechar Windows API functions.
 std::unique_ptr<char[]> WstringToCstring(const wchar_t *input);