Add --output-format command line option

Right now we have normal, terse, and json output. Lets add a parameter
that controls how to output results, instead of having options for
both terse and json outputs. If we are going to add a 4th output
type in the future, it's only going to get more messy.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fio.h b/fio.h
index 0064a1d..b2bbe93 100644
--- a/fio.h
+++ b/fio.h
@@ -526,7 +526,7 @@
 extern unsigned int nr_process, nr_thread;
 extern int shm_id;
 extern int groupid;
-extern int terse_output;
+extern int output_format;
 extern int temp_stall_ts;
 extern unsigned long long mlock_size;
 extern uintptr_t page_mask, page_size;
@@ -761,4 +761,10 @@
 extern const char *fio_get_arch_string(int);
 extern const char *fio_get_os_string(int);
 
+enum {
+	FIO_OUTPUT_TERSE	= 0,
+	FIO_OUTPUT_JSON,
+	FIO_OUTPUT_NORMAL,
+};
+
 #endif