r14898: This change is an attempt to improve the quality of the information that

is produced when a process exits abnormally.

First, we coalesce the core dumping code so that we greatly improve our
odds of being able to produce a core file, even in the case of a memory
fault. I've removed duplicates of dump_core() and split it in two to
reduce the amount of work needed to actually do the dump.

Second, we refactor the exit_server code path to always log an explanation
and a stack trace. My goal is to always produce enough log information
for us to be able to explain any server exit, though there is a risk
that this could produce too much log information on a flaky network.

Finally, smbcontrol has gained a smbd fault injection operation to test
the changes above. This is only enabled for developer builds.

source/include/debug.h

@@ -208,4 +208,8 @@ extern BOOL *DEBUGLEVEL_CLASS_ISSET;
             DEBUGLEVEL_CLASS[ DBGC_ALL   ] >= (level))  ) \
        && (dbgtext body) )
 
+/* Print a separator to the debug log. */
+#define DEBUGSEP(level)\
+	DEBUG((level),("===============================================================\n"))
+
 #endif