selftests/bpf: Prefer static linking for LLVM libraries

It is not always convenient to have LLVM libraries installed inside CI
rootfs images, thus request static libraries from llvm-config.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20240905081401.1894789-4-pulehui@huaweicloud.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/Makefile

@@ -202,11 +202,9 @@ ifeq ($(feature-llvm),1)
   LLVM_CONFIG_LIB_COMPONENTS := mcdisassembler all-targets
   # both llvm-config and lib.mk add -D_GNU_SOURCE, which ends up as conflict
   LLVM_CFLAGS  += $(filter-out -D_GNU_SOURCE,$(shell $(LLVM_CONFIG) --cflags))
-  LLVM_LDLIBS  += $(shell $(LLVM_CONFIG) --libs $(LLVM_CONFIG_LIB_COMPONENTS))
-  ifeq ($(shell $(LLVM_CONFIG) --shared-mode),static)
-    LLVM_LDLIBS += $(shell $(LLVM_CONFIG) --system-libs $(LLVM_CONFIG_LIB_COMPONENTS))
-    LLVM_LDLIBS += -lstdc++
-  endif
+  LLVM_LDLIBS  += $(shell $(LLVM_CONFIG) --link-static --libs $(LLVM_CONFIG_LIB_COMPONENTS))
+  LLVM_LDLIBS  += $(shell $(LLVM_CONFIG) --link-static --system-libs $(LLVM_CONFIG_LIB_COMPONENTS))
+  LLVM_LDLIBS  += -lstdc++
   LLVM_LDFLAGS += $(shell $(LLVM_CONFIG) --ldflags)
 endif