[PATCH bpf-next 2/2] selftests/bpf: Honor $(O) when figuring out paths

[Björn Töpel]

From: Björn Töpel <bjorn@xxxxxxxxxxxx>

When building the kselftests out-of-tree, e.g.
  | make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- \
  |   O=/tmp/kselftest headers
  | make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- \
  |  O=/tmp/kselftest HOSTCC=gcc FORMAT= \
  |  SKIP_TARGETS="arm64 ia64 powerpc sparc64 x86 sgx" \
  |  -C tools/testing/selftests gen_tar

the kselftest build would not pick up the correct GENDIR path, and
therefore not including autoconf.h.

Correct that by taking $(O) into consideration when figuring out the
GENDIR path.

Signed-off-by: Björn Töpel <bjorn@xxxxxxxxxxxx>
---
 tools/testing/selftests/bpf/Makefile | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index ad6b585e0d7c..daccc1b8573a 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -12,7 +12,11 @@ BPFDIR := $(LIBDIR)/bpf
 TOOLSINCDIR := $(TOOLSDIR)/include
 BPFTOOLDIR := $(TOOLSDIR)/bpf/bpftool
 APIDIR := $(TOOLSINCDIR)/uapi
+ifneq ($(O),)
+GENDIR := $(O)/include/generated
+else
 GENDIR := $(abspath ../../../../include/generated)
+endif
 GENHDR := $(GENDIR)/autoconf.h
 HOSTPKG_CONFIG := pkg-config
 
-- 
2.39.2