Use FNV hash function

git-svn-id: file:///svn/tokudb@118 c7de825b-a66e-492c-adef-691d508d4ae1

newbrt/hashfun.h

+// FNV Hash: From an idea sent by Glenn Fowler and Phong Vo to the IEEE POSIX 1003.2 committee.  Landon Curt Noll improved it.
+// See: http://isthe.com/chongo/tech/comp/fnv/
+static inline unsigned int hash_key (const unsigned char *key, unsigned long keylen) {
+    unsigned long i;
+    unsigned int hash=0;
+    for (i=0; i<keylen; i++, key++) {
+	hash *= 16777619;
+	hash ^= *key;
+    }
+    return hash;
+}
+
+#if 0
+static unsigned int hash_key (const char *key, ITEMLEN keylen) {
+    /* From Sedgewick.  There are probably better hash functions. */
+    unsigned int b    = 378551;
+    unsigned int a    = 63689;
+    unsigned int hash = 0;
+    ITEMLEN i;
+    for (i = 0; i < keylen; i++ ) {
+	hash = hash * a + key[i];
+	a *= b;
+    }
+    return hash;
+}
+#endif