package/linux-pam: select libxcrypt with glibc

Fix the following build failure raised since bump of glibc to version
2.39 in commit b5680f53d60acf8ff6010082f873438a39bd5d97:

/home/autobuild/autobuild/instance-6/output-1/per-package/linux-pam/host/bin/../lib/gcc/or1k-buildroot-linux-gnu/13.2.0/../../../../or1k-buildroot-linux-gnu/bin/ld: .libs/pam_pwhistory_la-opasswd.o: in function `compare_password':
opasswd.c:(.text+0x26c): undefined reference to `crypt'

Fixes: b5680f53d60acf8ff6010082f873438a39bd5d97
 - http://autobuild.buildroot.org/results/e17911978febb7b25112940a7c40037b3f98d491

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/linux-pam/Config.in

@@ -6,6 +6,7 @@ config BR2_PACKAGE_LINUX_PAM
 	depends on BR2_USE_MMU # fork()
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 # C11/stdatomic.h
 	select BR2_PACKAGE_FLEX
+	select BR2_PACKAGE_LIBXCRYPT if BR2_TOOLCHAIN_USES_GLIBC
 	help
 	  A Security Framework that Provides Authentication for
 	  Applications