selftests/landlock: Fix build with non-default pthread linking

Old toolchains require explicit -lpthread (e.g. on Debian 11).

Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Tahera Fahimi <fahimitahera@gmail.com>
Fixes: c899496 ("selftests/landlock: Test signal scoping for threads")
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20250115145409.312226-1-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>

Author: l0kod

tools/testing/selftests/landlock/Makefile

@@ -13,11 +13,11 @@ TEST_GEN_PROGS := $(src_test:.c=)
 TEST_GEN_PROGS_EXTENDED := true
 
 # Short targets:
-$(TEST_GEN_PROGS): LDLIBS += -lcap
+$(TEST_GEN_PROGS): LDLIBS += -lcap -lpthread
 $(TEST_GEN_PROGS_EXTENDED): LDFLAGS += -static
 
 include ../lib.mk
 
 # Targets with $(OUTPUT)/ prefix:
-$(TEST_GEN_PROGS): LDLIBS += -lcap
+$(TEST_GEN_PROGS): LDLIBS += -lcap -lpthread
 $(TEST_GEN_PROGS_EXTENDED): LDFLAGS += -static