kbuild: add stringify helper to quote a string passed to C files

Make $(squote)$(quote)...$(quote)$(squote) a helper macro.
I will reuse it in the next commit.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/Kbuild.include

@@ -32,6 +32,10 @@ real-prereqs = $(filter-out $(PHONY), $^)
 # Escape single quote for use in echo statements
 escsq = $(subst $(squote),'\$(squote)',$1)
 
+###
+# Quote a string to pass it to C files. foo => '"foo"'
+stringify = $(squote)$(quote)$1$(quote)$(squote)
+
 ###
 # Easy method for doing a status message
        kecho := :

scripts/Makefile.lib

@@ -97,7 +97,7 @@ target-stem = $(basename $(patsubst $(obj)/%,%,$@))
 # These flags are needed for modversions and compiling, so we define them here
 # $(modname_flags) defines KBUILD_MODNAME as the name of the module it will
 # end up in (or would, if it gets compiled in)
-name-fix = $(squote)$(quote)$(subst $(comma),_,$(subst -,_,$1))$(quote)$(squote)
+name-fix = $(call stringify,$(subst $(comma),_,$(subst -,_,$1)))
 basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget))
 modname_flags  = -DKBUILD_MODNAME=$(call name-fix,$(modname))