kbuild: error out if $(INSTALL_MOD_PATH) contains % or :

If the directory path given to INSTALL_MOD_PATH contains % or :,
the module_install fails.

% is used in pattern rules, and : as the separator of dependencies.

Bail out with a clearer error message.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>

scripts/Makefile.modinst

@@ -18,6 +18,9 @@ INSTALL_MOD_DIR ?= extra
 dst := $(MODLIB)/$(INSTALL_MOD_DIR)
 endif
 
+$(foreach x, % :, $(if $(findstring $x, $(dst)), \
+	$(error module installation path cannot contain '$x')))
+
 suffix-y				:=
 suffix-$(CONFIG_MODULE_COMPRESS_GZIP)	:= .gz
 suffix-$(CONFIG_MODULE_COMPRESS_XZ)	:= .xz