Make sure the consumer thread is properly notified by the main
thread both when there is a pending block and when the prefetching
is over.

(cherry picked from commit 234da8bfedce8661c2b8bc50f72632c240c4dfd8)

Spell check

There is no direct usage of terminfo library (ncurses) in ROOT. LLVM
uses it for color support. If LLVM detects tinfo library, tinfo will be
added for rootcling_tmp, rootcling, and libCling.so targets. Thus
explicit check for tinfo is not required.

This allows to use -DLLVM_ENABLE_TERMINFO=OFF to disable ncurses for
ROOT.

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>

The function HandleInterpreterException catches the NullDerefException.
Remove pre-exception longjmp code.