Add file extension for clang in libafl_cc/build.rs (#1237)

* Add CLANG and CLANG_PP env vars

Add CLANG and CLANG_PP env variables for Windows. Resolves issue if clang and llvm-config are not in the same location.

* Just add clang".exe" for windows

User should have llvm-config and clang.exe clang++.exe in the same directory anyways.

* Ran cargo fmt

libafl_cc/build.rs

@@ -150,7 +150,7 @@ fn build_pass(
 
         Some(r)
     } else if cfg!(windows) {
-        let r = Command::new(bindir_path.join("clang-cl"))
+        let r = Command::new(bindir_path.join("clang-cl.exe"))
             .arg("-v")
             .args(cxxflags)
             .arg(src_dir.join(src_file))
@@ -234,8 +234,16 @@ pub const LIBAFL_CC_LLVM_VERSION: Option<usize> = None;
     let llvm_bindir = exec_llvm_config(&["--bindir"]);
     let bindir_path = Path::new(&llvm_bindir);
 
-    let clang = bindir_path.join("clang");
-    let clangcpp = bindir_path.join("clang++");
+    let clang;
+    let clangcpp;
+
+    if cfg!(windows) {
+        clang = bindir_path.join("clang.exe");
+        clangcpp = bindir_path.join("clang++.exe");
+    } else {
+        clang = bindir_path.join("clang");
+        clangcpp = bindir_path.join("clang++");
+    }
 
     if !clang.exists() {
         println!("cargo:warning=Failed to find clang frontend.");