Use DJB2a hash algorithm in getHostHash()

src/common.h

@@ -165,10 +165,10 @@ static void getHostName(char* hostname, int maxlen) {
 #include <stdint.h>
 
 static uint64_t getHostHash(const char* string) {
-  // Based on DJB2, result = result * 33 + char
+  // Based on DJB2a, result = result * 33 ^ char
   uint64_t result = 5381;
   for (int c = 0; string[c] != '\0'; c++){
-    result = ((result << 5) + result) + string[c];
+    result = ((result << 5) + result) ^ string[c];
   }
   return result;
 }