remove second definition of kstring

mmpriv.h

@@ -4,6 +4,7 @@
 #include <assert.h>
 #include "minimap.h"
 #include "bseq.h"
+#include "kseq.h"
 
 #define MM_PARENT_UNSET   (-1)
 #define MM_PARENT_TMP_PRI (-2)
@@ -35,14 +36,6 @@
 extern "C" {
 #endif
 
-#ifndef KSTRING_T
-#define KSTRING_T kstring_t
-typedef struct __kstring_t {
-	unsigned l, m;
-	char *s;
-} kstring_t;
-#endif
-
 typedef struct {
 	int n_u, n_a;
 	uint64_t *u;