Clean up vlc_iconv prototype

include/vlc_common.h

@@ -1085,7 +1085,7 @@ VLC_EXPORT( char *, vlc_wraptext, ( const char *, int ) );
 /* iconv wrappers (defined in src/extras/libc.c) */
 typedef void *vlc_iconv_t;
 VLC_EXPORT( vlc_iconv_t, vlc_iconv_open, ( const char *, const char * ) );
-VLC_EXPORT( size_t, vlc_iconv, ( vlc_iconv_t, char **, size_t *, char **, size_t * ) );
+VLC_EXPORT( size_t, vlc_iconv, ( vlc_iconv_t, const char **, size_t *, char **, size_t * ) );
 VLC_EXPORT( int, vlc_iconv_close, ( vlc_iconv_t ) );
 
 /* execve wrapper (defined in src/extras/libc.c) */

include/vlc_symbols.h

@@ -188,7 +188,7 @@ struct module_symbols_t
     char ** (*vlc_parse_cmdline_inner) (const char *, int *);
     char * (*vlc_wraptext_inner) (const char *, int);
     vlc_iconv_t (*vlc_iconv_open_inner) (const char *, const char *);
-    size_t (*vlc_iconv_inner) (vlc_iconv_t, char **, size_t *, char **, size_t *);
+    size_t (*vlc_iconv_inner) (vlc_iconv_t, const char **, size_t *, char **, size_t *);
     int (*vlc_iconv_close_inner) (vlc_iconv_t);
     char * (*vlc_dgettext_inner) (const char *package, const char *msgid);
     demux_t * (*__demux2_New_inner) (vlc_object_t *p_obj, char *psz_access, char *psz_demux, char *psz_path, stream_t *s, es_out_t *out, vlc_bool_t);

src/extras/libc.c

@@ -613,11 +613,12 @@ vlc_iconv_t vlc_iconv_open( const char *tocode, const char *fromcode )
 #endif
 }
 
-size_t vlc_iconv( vlc_iconv_t cd, char **inbuf, size_t *inbytesleft,
+size_t vlc_iconv( vlc_iconv_t cd, const char **inbuf, size_t *inbytesleft,
                   char **outbuf, size_t *outbytesleft )
 {
 #if defined(HAVE_ICONV)
-    return iconv( cd, inbuf, inbytesleft, outbuf, outbytesleft );
+    return iconv( cd, (ICONV_CONST char **)inbuf, inbytesleft,
+                  outbuf, outbytesleft );
 #else
     int i_bytes;