kbuild: rust: move rust/target.json to scripts/

scripts/ is a better place to generate files used treewide.

With target.json moved to scripts/, you do not need to add target.json
to no-clean-files or MRPROPER_FILES.

'make clean' does not visit scripts/, but 'make mrproper' does.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Tested-by: Miguel Ojeda <ojeda@kernel.org>

Makefile

@@ -569,7 +569,7 @@ KBUILD_CFLAGS   := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \
 		   -std=gnu11
 KBUILD_CPPFLAGS := -D__KERNEL__
 KBUILD_RUSTFLAGS := $(rust_common_flags) \
-		    --target=$(objtree)/rust/target.json \
+		    --target=$(objtree)/scripts/target.json \
 		    -Cpanic=abort -Cembed-bitcode=n -Clto=n \
 		    -Cforce-unwind-tables=n -Ccodegen-units=1 \
 		    -Csymbol-mangling-version=v0 \
@@ -1606,7 +1606,7 @@ MRPROPER_FILES += include/config include/generated          \
 		  certs/x509.genkey \
 		  vmlinux-gdb.py \
 		  *.spec \
-		  rust/target.json rust/libmacros.so
+		  rust/libmacros.so
 
 # clean - Delete most, but leave enough to build external modules
 #