Use debug version of MSVC runtime library on debug

Fixed #1230

Author: NobodyXu

src/lib.rs

@@ -1945,10 +1945,19 @@ impl Build {
                     None => {
                         let features = self.getenv("CARGO_CFG_TARGET_FEATURE");
                         let features = features.as_deref().unwrap_or_default();
+                        let debug = self.get_debug();
                         if features.to_string_lossy().contains("crt-static") {
-                            "-MT"
+                            if debug {
+                                "-MTd"
+                            } else {
+                                "-MT"
+                            }
                         } else {
-                            "-MD"
+                            if debug {
+                                "-MDd"
+                            } else {
+                                "-MD"
+                            }
                         }
                     }
                 };