Revert "lib: Async functions cannot be started without a mainloop"

This reverts commit 700c5791.

We don't need a poll setup to be able to call sync functions, which then
use async functions for implementation internally.

Closes: #124

Conflicts:
	libfprint/fpi-async.c

libfprint/fpi-async.c

@@ -21,7 +21,6 @@
 
 #include "fp_internal.h"
 #include "fpi-async.h"
-#include "fpi-poll.h"
 
 #include <config.h>
 #include <errno.h>
@@ -178,7 +177,6 @@ API_EXPORTED int fp_async_enroll_start(struct fp_dev *dev,
 	int r;
 
 	g_return_val_if_fail(dev != NULL, -ENODEV);
-	g_return_val_if_fail (fpi_poll_is_setup(), -EIO);
 	g_return_val_if_fail (callback != NULL, -EINVAL);
 
 	drv = dev->drv;
@@ -295,7 +293,6 @@ API_EXPORTED int fp_async_verify_start(struct fp_dev *dev,
 	int r;
 
 	g_return_val_if_fail(dev != NULL, -ENODEV);
-	g_return_val_if_fail (fpi_poll_is_setup(), -EIO);
 	g_return_val_if_fail (callback != NULL, -EINVAL);
 
 	drv = dev->drv;
@@ -430,7 +427,6 @@ API_EXPORTED int fp_async_identify_start(struct fp_dev *dev,
 	int r;
 
 	g_return_val_if_fail(dev != NULL, -ENODEV);
-	g_return_val_if_fail (fpi_poll_is_setup(), -EIO);
 	g_return_val_if_fail (callback != NULL, -EINVAL);
 
 	drv = dev->drv;
@@ -565,7 +561,6 @@ API_EXPORTED int fp_async_capture_start(struct fp_dev *dev, int unconditional,
 	int r;
 
 	g_return_val_if_fail(dev != NULL, -ENODEV);
-	g_return_val_if_fail (fpi_poll_is_setup(), -EIO);
 	g_return_val_if_fail (callback != NULL, -EINVAL);
 
 	drv = dev->drv;