Add support for other ways of triggering intermediate result outputs

Fio has support for using the USR1 signal to dump the current
results while continuing to run. Add a --status-interval parameter
to allow this to be configured to automatically happen every X
seconds.

There's also support for signaling fio through the file system. To
do that, simply touch /tmp/fio-dump-status. When fio sees this file,
it will unlink and dump the current results.

A small tweak is needed for the file approach to work in Windows.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/parse.h b/parse.h
index b9da7b9..cf15ce0 100644
--- a/parse.h
+++ b/parse.h
@@ -89,6 +89,7 @@
 extern void strip_blank_end(char *);
 extern int str_to_decimal(const char *, long long *, int, void *);
 extern int check_str_bytes(const char *p, long long *val, void *data);
+extern int check_str_time(const char *p, long long *val);
 extern int str_to_float(const char *str, double *val);
 
 /*