+ correct pathname used in Ada95 sample programs for explain.txt, to
work with test-packages.
+ improve tracemunch:
+ keep track of TERMINAL* values
+ if tracing was first turned on after initialization, attempt to
show distinct screen, window and terminal names anyway.
+ ensure that GCC_NORETURN is defined in term.h, because the prototype
for exit_terminfo() uses it (report by Werner Fink).