Add XXX_PROCESS_ALT mecchanism
diff --git a/library/md5.c b/library/md5.c
index 62f619b..5eef65d 100644
--- a/library/md5.c
+++ b/library/md5.c
@@ -107,6 +107,7 @@
     ctx->state[3] = 0x10325476;
 }
 
+#if !defined(POLARSSL_MD5_PROCESS_ALT)
 void md5_process( md5_context *ctx, const unsigned char data[64] )
 {
     uint32_t X[16], A, B, C, D;
@@ -229,6 +230,7 @@
     ctx->state[2] += C;
     ctx->state[3] += D;
 }
+#endif /* !POLARSSL_MD5_PROCESS_ALT */
 
 /*
  * MD5 process buffer