mingw: implement syslog

Syslog does not usually exist on Windows, so implement our own using
Window's ReportEvent mechanism.

Strings containing "%1" gets expanded into them selves by ReportEvent,
resulting in an unreadable string. "%2" and above is not a problem.
Unfortunately, on Windows an IPv6 address can contain "%1", so expand
"%1" to "% 1" before reporting. "%%1" is also a problem for ReportEvent,
but that string cannot occur in an IPv6 address.

Signed-off-by: Mike Pape <dotzenlabs@gmail.com>
Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

compat/win32/syslog.h

@@ -0,0 +1,20 @@
+#ifndef SYSLOG_H
+#define SYSLOG_H
+
+#define LOG_PID     0x01
+
+#define LOG_EMERG   0
+#define LOG_ALERT   1
+#define LOG_CRIT    2
+#define LOG_ERR     3
+#define LOG_WARNING 4
+#define LOG_NOTICE  5
+#define LOG_INFO    6
+#define LOG_DEBUG   7
+
+#define LOG_DAEMON  (3<<3)
+
+void openlog(const char *ident, int logopt, int facility);
+void syslog(int priority, const char *fmt, ...);
+
+#endif /* SYSLOG_H */