VxWorks: use wr-cc for C file, use wr-c++ for CPP file (#546)

Author: bpangWR

src/lib.rs

@@ -2002,7 +2002,11 @@ impl Build {
                 {
                     "clang".to_string()
                 } else if target.contains("vxworks") {
-                    "wr-c++".to_string()
+                    if self.cpp {
+                        "wr-c++".to_string()
+                    } else {
+                        "wr-cc".to_string()
+                    }
                 } else if self.get_host()? != target {
                     let prefix = self.prefix_for_target(&target);
                     match prefix {