(ITS#8442) Uninitialized diagnosticMessage in back-meta

[h . b . furuseth]

Full_Name: Hallvard B Furuseth
Version: 2.4.41 and later
OS: 
URL: 
Submission from: (NULL) (81.191.45.31)
Submitted by: hallvard


meta_back_search() does a goto past
  const char *save_text = rs->sr_text;
which is later "restored" to rs->sr_text.
Fixing.