Fix const qualifier (fix compiler warning)

src/mem.c

@@ -335,7 +335,7 @@ void *n_malloc(int size, const char *file, int line)
 #ifdef DEBUG_MEM
   size_t size2;
   int i = 0;
-  char *p;
+  const char *p;
 #endif
 
   x = (void *) malloc(size);
@@ -378,7 +378,7 @@ void *n_realloc(void *ptr, int size, const char *file, int line)
   void *x;
 #ifdef DEBUG_MEM
   int i = 0;
-  char *p;
+  const char *p;
 #endif
 
   /* ptr == NULL is valid. Avoiding duplicate code further down */

src/misc.c

@@ -310,7 +310,8 @@ char *newsplit(char **rest)
 void maskaddr(const char *s, char *nw, int type)
 {
   int d = type % 5, num = 1;
-  char *p, *u = 0, *h = 0, *ss;
+  const char *p, *u = 0, *h = 0;
+  char *ss;
 
   /* Look for user and host.. */
   ss = (char *)s;