md5: forced to use function names with leading underscores

Commented out the surrounding '#ifdef _LIBC' to build md5.o with
leading underscores. This is required to match the prototypes defined
in md5.h.

common/md5.c

@@ -28,7 +28,7 @@
 
 #include "md5.h"
 
-#ifdef _LIBC
+/* #ifdef _LIBC */
 # include <endian.h>
 # if __BYTE_ORDER == __BIG_ENDIAN
 #  define WORDS_BIGENDIAN 1
@@ -42,7 +42,7 @@
 # define md5_read_ctx __md5_read_ctx
 # define md5_stream __md5_stream
 # define md5_buffer __md5_buffer
-#endif
+/* #endif */
 
 #ifdef WORDS_BIGENDIAN
 # define SWAP(n)                                                        \