diagnostics: update signature of some callbacks

diagnostics: update signature of some callbacks

No functional change intended.

gcc/cp/ChangeLog:
	* error.cc (cp_adjust_diagnostic_info): Convert "context" arg from
	ptr to const &.

gcc/ChangeLog:
	* diagnostics/context.cc (context::get_any_inlining_info): Convert
	"context" arg of m_set_locations_cb from ptr to const &.
	(context::report_diagnostic): Convert "context" arg of
	m_adjust_diagnostic_info from ptr to const &.
	* diagnostics/context.h (context::set_locations_callback_t):
	Likewise.
	(context::set_adjust_diagnostic_info_callback): Likewise.
	(context::m_adjust_diagnostic_info): Likewise.
	* tree-diagnostic.cc (set_inlining_locations): Likewise.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>