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/include/hash.h

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef HASH_H
+#define HASH_H
+
+static inline unsigned int hash_str(const char *s)
+{
+	/* fnv32 hash */
+	unsigned int hash = 2166136261U;
+
+	for (; *s; s++)
+		hash = (hash ^ *s) * 0x01000193;
+	return hash;
+}
+
+#endif /* HASH_H */