scripts: move hash function from scripts/kconfig/ to scripts/include/

This function was originally added by commit 8af27e1dc4 ("fixdep: use
hash table instead of a single array").

Move it to scripts/include/ so that other host programs can use it.

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

scripts/kconfig/lkc.h

@@ -51,7 +51,6 @@ static inline void xfwrite(const void *str, size_t len, size_t count, FILE *out)
 }
 
 /* util.c */
-unsigned int strhash(const char *s);
 const char *file_lookup(const char *name);
 
 /* lexer.l */