Fixed compiler warnings.

Author: Fotis Panagiotopoulos

nshlib/nsh_command.c

@@ -1160,7 +1160,7 @@ int nsh_extmatch_count(FAR char *name, FAR int *matches, int namelen)
     defined(CONFIG_READLINE_HAVE_EXTMATCH)
 FAR const char *nsh_extmatch_getname(int index)
 {
-  DEBUGASSERT(index > 0 && index <= NUM_CMDS);
+  DEBUGASSERT(index > 0 && index <= (int)NUM_CMDS);
   return  g_cmdmap[index].cmd;
 }
 #endif

nshlib/nsh_fsutils.c

@@ -262,7 +262,7 @@ int nsh_readfile(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd,
         {
           /* Successful read.  Make sure that the buffer is null terminated */
 
-          DEBUGASSERT(nread <= remaining);
+          DEBUGASSERT(nread <= (ssize_t)remaining);
           ntotal += nread;
           buffer[ntotal] = '\0';