MSL_C cleanup (#238)

* clean up MSL_C files according to prime decomp

* remove asm

include/errno.h

@@ -1,6 +1,20 @@
 #ifndef MSL_COMMON_SRC_ERRNO_H
 #define MSL_COMMON_SRC_ERRNO_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define ENOERR 0
+#define EDOM 33
+#define ERANGE 34
+#define EFPOS 40
+#define ESIGPARM 36
+
 extern int errno;
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* MSL_COMMON_SRC_ERRNO_H */