Fix discarded-qualifiers Warning.

[MeinhardZhou]

• unsupporeted_term should be const char*
• linenoiseEditMore should be const char*, but linenoiseEditFeed() return char *, so add a local heap-allocate variable.

Warning:

../thirdparty/linenoise/linenoise.c:122:36: warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
  122 | static char *unsupported_term[] = {"dumb","cons25","emacs",NULL};
      |                                    ^~~~~~
../thirdparty/linenoise/linenoise.c:122:43: warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
  122 | static char *unsupported_term[] = {"dumb","cons25","emacs",NULL};
      |                                           ^~~~~~~~
../thirdparty/linenoise/linenoise.c:122:52: warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
  122 |  char *unsupported_term[] = {"dumb","cons25","emacs",NULL};
      |                                              ^~~~~~~

../thirdparty/linenoise/linenoise.c:908:27: warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
  908 | char *linenoiseEditMore = "If you see this, you are misusing the API: when linenoiseEditFeed() is called, if it returns linenoiseEditMore the user is yet editing the line. See the README file for more information.";
      |                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~