libgpiod: new package

Add a package containing a C library and a set of command-line tools
for controlling GPIOs from user space using the new character device
interface on linux.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
[Thomas:
 - add comment about autoreconf=yes (suggested by Romain Naour)
 - add more conventional syntax for the --{enable,disable}-tools usage
   (suggested by Romain Naour)
 - add patch to fix musl build.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
diff --git a/package/Config.in b/package/Config.in
index 1766089..560a52c 100644
--- a/package/Config.in
+++ b/package/Config.in
@@ -1046,6 +1046,7 @@
 	source "package/libfreefare/Config.in"
 	source "package/libftdi/Config.in"
 	source "package/libftdi1/Config.in"
+	source "package/libgpiod/Config.in"
 	source "package/libgudev/Config.in"
 	source "package/libhid/Config.in"
 	source "package/libiio/Config.in"