package/libpthsem: update project URL

The previous site went offline, the last entry dates back to April 2026:
https://web.archive.org/web/20260401000000*/http://www.auto.tuwien.ac.at/~mkoegler/pth/

Update _SITE to the bcusdk project which depends on libpthsem and stores
the original tarball. Update project URL to github mirror provided by the
linknx project which also depends on libpthsem.

Fixes download error:

ERROR: while checking hashes from package/libpthsem/libpthsem.hash
ERROR: pthsem_2.0.8.tar.gz has wrong sha256 hash:
ERROR: expected: 4024cafdd5d4bce2b1778a6be5491222c3f6e7ef1e43971264c451c0012c5c01
ERROR: got     : 01d9027268f27aab3ca5c6c649a7f7a444db5bc889e496d80c8704e4e120346e
ERROR: Incomplete download, or man-in-the-middle (MITM) attack

Fixes:
https://autobuild.buildroot.net/results/0d9/0d9e957540d15302ac55bc5a2207db0c45279b37/

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/libpthsem/Config.in

@@ -5,7 +5,7 @@ config BR2_PACKAGE_LIBPTHSEM
 	  GNU pth is a user mode multi threading library. pthsem is an
 	  extend version, with support for semaphores added.
 
-	  http://www.auto.tuwien.ac.at/~mkoegler/pth/
+	  https://github.com/linknx/pthsem
 
 if BR2_PACKAGE_LIBPTHSEM
 

package/libpthsem/libpthsem.mk

@@ -6,7 +6,7 @@
 
 LIBPTHSEM_VERSION = 2.0.8
 LIBPTHSEM_SOURCE = pthsem_$(LIBPTHSEM_VERSION).tar.gz
-LIBPTHSEM_SITE = http://www.auto.tuwien.ac.at/~mkoegler/pth
+LIBPTHSEM_SITE = https://sourceforge.net/projects/bcusdk/files/pthsem
 LIBPTHSEM_LICENSE = LGPL-2.1+
 LIBPTHSEM_LICENSE_FILES = COPYING
 LIBPTHSEM_AUTORECONF = YES