ck_ht: Remove stale comment about only working for 64bits.

As reported by Andrey V. Elsukov, ck_ht can now run on 32bits machine, so
remove the comment that claims it only works for 64bits.

src/ck_ht.c

@@ -30,9 +30,6 @@
 /*
  * This implementation borrows several techniques from Josh Dybnis's
  * nbds library which can be found at http://code.google.com/p/nbds
- *
- * This release currently only includes support for 64-bit platforms.
- * We can address 32-bit platforms in a future release.
  */
 #include <ck_cc.h>
 #include <ck_md.h>