[PATCH] rust: build: Define MODULE macro iif the CONFIG_MODULES is enabled

[WANG Rui]

The LoongArch does not currently support modules when built with clang.
A pre-processor error is expected on building modules, that's caused by:

 #if defined(MODULE) && defined(CONFIG_AS_HAS_EXPLICIT_RELOCS)
 # if __has_attribute(model)
 #  define PER_CPU_ATTRIBUTES __attribute__((model("extreme")))
 # else
 #  error compiler support for the model attribute is necessary when a recent assembler is used
 # endif
 #endif

This also happens with bindgen too, so it would be better to define
MODULE macro if and only if the CONFIG_MODULES is enabled.

Signed-off-by: WANG Rui <wangrui@xxxxxxxxxxx>
---
 rust/Makefile | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/rust/Makefile b/rust/Makefile
index fc8cdcfcc9e5..d31d9fa27ef0 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -295,12 +295,16 @@ endif
 
 bindgen_c_flags_final = $(bindgen_c_flags_lto) -D__BINDGEN__
 
+ifdef CONFIG_MODULES
+bindgen_c_flags_final += -DMODULE
+endif
+
 quiet_cmd_bindgen = BINDGEN $@
       cmd_bindgen = \
 	$(BINDGEN) $< $(bindgen_target_flags) \
 		--use-core --with-derive-default --ctypes-prefix core::ffi --no-layout-tests \
 		--no-debug '.*' \
-		-o $@ -- $(bindgen_c_flags_final) -DMODULE \
+		-o $@ -- $(bindgen_c_flags_final) \
 		$(bindgen_target_cflags) $(bindgen_target_extra)
 
 $(obj)/bindings/bindings_generated.rs: private bindgen_target_flags = \
-- 
2.41.0