Windows, CROSSTOOL: Add support for clang-cl.exe

Related #4811

clang-cl is a driver program for clang that attempts to be compatible with MSVC?s cl.exe, which means we can just use MSVC's CROSSTOOL with clang-cl.exe. See more from https://clang.llvm.org/docs/MSVCCompatibility.html

Closes #6553.

Change-Id: I907fc71a51e11c0c204b00c845d14b40e7c9f55f
PiperOrigin-RevId: 219798300

tools/cpp/cc_configure.bzl

diff --git a/tools/cpp/cc_configure.bzl b/tools/cpp/cc_configure.bzl
index cf4c389..699c348 100644
--- a/tools/cpp/cc_configure.bzl
+++ b/tools/cpp/cc_configure.bzl
@@ -72,6 +72,8 @@
         "BAZEL_USE_LLVM_NATIVE_COVERAGE",
         "BAZEL_VC",
         "BAZEL_VS",
+        "BAZEL_LLVM",
+        "USE_CLANG_CL",
         "CC",
         "CC_CONFIGURE_DEBUG",
         "CC_TOOLCHAIN_NAME",