analyzer: convert various enums to "enum class"

analyzer: convert various enums to "enum class"

Modernization; no functional change intended.

gcc/analyzer/ChangeLog:
	* access-diagram.cc: Convert enum access_direction to
	"enum class".
	* bounds-checking.cc: Likewise.
	* checker-event.cc: Convert enum event_kind to "enum class".
	* checker-event.h: Likewise.
	* checker-path.cc: Likewise.
	* common.h: Convert enum access_direction to "enum class".
	* constraint-manager.cc: Convert enum bound_kind to "enum class".
	* constraint-manager.h: Likewise.
	* diagnostic-manager.cc: Convert enum event_kind to "enum class".
	* engine.cc: Convert enum status to "enum class".
	* exploded-graph.h: Likewise.
	* infinite-loop.cc: Likewise.
	* kf-lang-cp.cc: Convert enum poison_kind to "enum class".
	* kf.cc: Likewise.
	* region-model-manager.cc: Likewise.
	* region-model.cc: Likewise; also for enum access_direction.
	* svalue.cc: Likewise.
	* svalue.h: Likewise.

gcc/testsuite/ChangeLog:
	* gcc.dg/plugin/analyzer_cpython_plugin.cc: Convert
	enum poison_kind to "enum class".

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