Remove bad fclose() calls introduced in e5b0b42b

  These fclose calls were added by mistake during a code cleanup during port to
  xrootd 3.3.x . The bug is fatal when authentication is enabled and affects all
  5.34 versions 5.34/06 to 5.34/09 .
Revert no-optimization for JIT; we need it until the CodeGen bug is understood!

This reverts commit 8f85c529125ca622ec95dbc3ed92ead815dc555d.