build: Don't overwrite clang-cl with clang for ARM64 Windows builds

When cross-compiling for Windows, it's common to use the `clang-cl`
driver which supports parsing `cl.exe`-like arguments.  When `ring`
however overwrites this compiler with `clang`, existing user arguments
in i.e. `CFLAGS` are not compatible resulting in various "unknown
argument" errors such as for `-vctoolsdir` and `-winsdkdir`.

As pointed out in the original ARM64 Windows support PR, compiling
`ring` with `clang-cl` works equally well as `clang`: allow that by not
overwriting the compiler with `clang` if it's already `clang-cl`, to not
have to sort out incompatible arguments.

Cargo.toml

@@ -227,3 +227,7 @@ default-members = [
     ".",
     "cavp"
 ]
+
+[patch.crates-io]
+# https://github.com/rust-lang/cc-rs/pull/1357
+cc = { git = "https://github.com/rust-lang/cc-rs", rev = "5f58a7c" }

build.rs

@@ -547,9 +547,13 @@ fn obj_path(out_dir: &Path, src: &Path) -> PathBuf {
 
 fn configure_cc(c: &mut cc::Build, target: &Target, c_root_dir: &Path, include_dir: &Path) {
     let compiler = c.get_compiler();
-    // FIXME: On Windows AArch64 we currently must use Clang to compile C code
-    let compiler = if target.os == WINDOWS && target.arch == AARCH64 && !compiler.is_like_clang() {
-        let _ = c.compiler("clang");
+    // FIXME: On Windows AArch64 we currently must use clang or clang-cl to compile C code
+    let compiler = if target.os == WINDOWS
+        && target.arch == AARCH64
+        && !compiler.is_like_clang()
+        && !compiler.is_like_clang_cl()
+    {
+        c.compiler("clang");
         c.get_compiler()
     } else {
         compiler