bug fix a segfault on loading redchan file descriptor

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@44394 15284696-431f-4ddb-bdfa-cd5b030d7da7

imagery/i.vi/main.c

@@ -210,7 +210,7 @@ int main(int argc, char *argv[])
                 || !(input6->answer) || !(input7->answer)) )
 	G_fatal_error(_("gvi index requires blue, green, red, nir, chan5 and chan7 maps"));
 
-    if ((infd_redchan = Rast_open_old(redchan, "")) < 0)
+    infd_redchan = Rast_open_old(redchan, "");
     inrast_redchan = Rast_allocate_d_buf();
 
     if (nirchan) {