Fix MSVC warning C4127 in HASH_BLOOM_TEST (#261)

MSVC `-W4` gives "warning C4127: conditional expression is constant"
for `if (1 != 0)`, but no warning for `if (1)`. Use the latter instead
of the former. In fact, the comparison against zero should really be
all the way down in `HASH_BLOOM_BITTEST`.

No functional change intended.

Thanks to @noodlecollie for the patch!

Author: Quuxplusone

src/uthash.h

@@ -159,7 +159,7 @@ do {
   if (head) {                                                                    \
     unsigned _hf_bkt;                                                            \
     HASH_TO_BKT(hashval, (head)->hh.tbl->num_buckets, _hf_bkt);                  \
-    if (HASH_BLOOM_TEST((head)->hh.tbl, hashval) != 0) {                         \
+    if (HASH_BLOOM_TEST((head)->hh.tbl, hashval)) {                              \
       HASH_FIND_IN_BKT((head)->hh.tbl, hh, (head)->hh.tbl->buckets[ _hf_bkt ], keyptr, keylen, hashval, out); \
     }                                                                            \
   }                                                                              \
@@ -196,7 +196,7 @@ do {
 } while (0)
 
 #define HASH_BLOOM_BITSET(bv,idx) (bv[(idx)/8U] |= (1U << ((idx)%8U)))
-#define HASH_BLOOM_BITTEST(bv,idx) (bv[(idx)/8U] & (1U << ((idx)%8U)))
+#define HASH_BLOOM_BITTEST(bv,idx) ((bv[(idx)/8U] & (1U << ((idx)%8U))) != 0)
 
 #define HASH_BLOOM_ADD(tbl,hashv)                                                \
   HASH_BLOOM_BITSET((tbl)->bloom_bv, ((hashv) & (uint32_t)((1UL << (tbl)->bloom_nbits) - 1U)))
@@ -208,7 +208,7 @@ do {
 #define HASH_BLOOM_MAKE(tbl,oomed)
 #define HASH_BLOOM_FREE(tbl)
 #define HASH_BLOOM_ADD(tbl,hashv)
-#define HASH_BLOOM_TEST(tbl,hashv) (1)
+#define HASH_BLOOM_TEST(tbl,hashv) 1
 #define HASH_BLOOM_BYTELEN 0U
 #endif