libsigrok: use libhidapi's hid_init() instead of our usbhid(3)'s one

Because our usbhid(3) defines hid_init(3), the libhidapi's one has been
renamed to hidapi_hid_init(). Sigrok expects the libhidapi one. This led
to build failures on ld.bfd arches, and probably runtime errors on other
arches.

As such, redefine the hid_init() call to hidapi_hid_init().

OK sthen@, kmos@ (who build tested on sparc64) and
"seems ok to me" bentley@ (maintainer)

comms/sigrok/libsigrok/Makefile

@@ -1,11 +1,11 @@
-# $OpenBSD: Makefile,v 1.11 2021/03/06 22:42:43 bentley Exp $
+# $OpenBSD: Makefile,v 1.12 2021/04/12 11:22:33 cwen Exp $
 
 COMMENT =		sigrok hardware driver library
 
 SIGROK_PROJECT =	libsigrok
 SIGROK_VERSION =	0.5.2
 MODPY_EGG_VERSION =	${SIGROK_VERSION}
-REVISION =		0
+REVISION =		1
 
 SHARED_LIBS +=  sigrok                    0.1 # 0.0
 SHARED_LIBS +=  sigrokcxx                 0.1 # 4.0

comms/sigrok/libsigrok/patches/patch-src_backend_c

@@ -0,0 +1,22 @@
+$OpenBSD: patch-src_backend_c,v 1.1 2021/04/12 11:22:33 cwen Exp $
+
+Fix for:
+src/backend.c:613:6: warning: implicit declaration of function 'hid_init'
+is invalid in C99
+On ld.bfd arches, this led to undefined references at build time.
+
+It appears that comms/libhidapi redefines hid_init(3) to hidapi_hid_init().
+
+Index: src/backend.c
+--- src/backend.c.orig
++++ src/backend.c
+@@ -23,6 +23,9 @@
+ #ifdef _WIN32
+ #include <winsock2.h>
+ #endif
++#ifdef __OpenBSD__
++#define hid_init hidapi_hid_init
++#endif
+ #include <libsigrok/libsigrok.h>
+ #include "libsigrok-internal.h"
+