New server option -E to choose what to do on oops

Three options: abort, crash-dump, nothing.  crash-dump works by
aborting a fork.  It isn't implemented for Windows.

The oops action is no longer tied to daemon mode, but -d still implies
-E abort for convenience.

include/misc.h

@@ -69,7 +69,12 @@
 #define hours(x)	(60*60*(x))
 #define days(x)		(60*60*24*(x))
 
-extern int debug;
+enum oops_action {
+    OOPS_ABORT,
+    OOPS_CRASH_DUMP,
+    OOPS_NOTHING
+};
+extern enum oops_action oops_action;
 
 /*
  * If EXPR is true, an internal error occured.