[PATCH] Makefile: add $(srctree) to dependency of compile_commands.json target

[Alexandre Courbot]

When trying to build the compile_commands.json target from an external
module's directory, the following error is displayed:

	make[1]: *** No rule to make target 'scripts/clang-tools/gen_compile_commands.py',
	needed by 'compile_commands.json'. Stop.

This appears to be because gen_compile_commands.py is looked up using
relative path, which doesn't exist from the module's source tree.
Prefixing the dependency with $(srctree) fixes the problem.

Signed-off-by: Alexandre Courbot <gnurou@xxxxxxxxx>
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 8ad55d6e7b60..52d7dfe4212a 100644
--- a/Makefile
+++ b/Makefile
@@ -1980,7 +1980,7 @@ nsdeps: modules
 quiet_cmd_gen_compile_commands = GEN     $@
       cmd_gen_compile_commands = $(PYTHON3) $< -a $(AR) -o $@ $(filter-out $<, $(real-prereqs))
 
-$(extmod_prefix)compile_commands.json: scripts/clang-tools/gen_compile_commands.py \
+$(extmod_prefix)compile_commands.json: $(srctree)/scripts/clang-tools/gen_compile_commands.py \
 	$(if $(KBUILD_EXTMOD),, vmlinux.a $(KBUILD_VMLINUX_LIBS)) \
 	$(if $(CONFIG_MODULES), $(MODORDER)) FORCE
 	$(call if_changed,gen_compile_commands)
-- 
2.46.0