Fix Fortran regression with variables in nested functions

Fix Fortran regression with variables in nested functions

Sergio pointed out that commit commit aa3b6533 ("Allow nested function
displays") regressed a few gdb.fortran tests.  I was able to reproduce
these failures with gcc head.

The bug is that some spots calling contained_in will in fact do the
wrong thing if nested functions are considered as contained.  In the
particular case of the Fortran regression, it was the call in
block_innermost_frame, being called from get_hosting_frame -- in this
case, the caller is specifically trying to avoid the nested case.

This patch fixes the problem by adding an "allow_nested" parameter to
contained_in, essentially reverting the change for most callers.

gdb/ChangeLog
2019-08-19  Tom Tromey  <tromey@adacore.com>

	* printcmd.c (do_one_display, info_display_command): Update.
	* block.h (contained_in): Return bool.  Add allow_nested
	parameter.
	* block.c (contained_in): Return bool.  Add allow_nested
	parameter.