deps: float fix for building HdrHistogram on Win x86

From:
mcollina/native-hdr-histogram@c63e97151dcff9b9aed1d8ea5e4f5964c69be32fideps:

PR-URL: #25378
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

Author: jasnell

deps/histogram/src/hdr_histogram.c

@@ -91,14 +91,29 @@ static int64_t power(int64_t base, int64_t exp)
 }
 
 #if defined(_MSC_VER)
-#pragma intrinsic(_BitScanReverse64)
+#  if defined(_WIN64)
+#    pragma intrinsic(_BitScanReverse64)
+#  else
+#    pragma intrinsic(_BitScanReverse)
+#  endif
 #endif
 
 static int32_t get_bucket_index(const struct hdr_histogram* h, int64_t value)
 {
 #if defined(_MSC_VER)
     uint32_t leading_zero = 0;
-    _BitScanReverse64(&leading_zero, value | h->sub_bucket_mask);
+    int64_t masked_value = value | h->sub_bucket_mask;
+#  if defined(_WIN64)
+    _BitScanReverse64(&leading_zero, masked_value);
+#  else
+    uint32_t high = masked_value >> 32;
+    if  (_BitScanReverse(&leading_zero, high)) {
+      leading_zero += 32;
+    } else {
+      uint32_t low = masked_value & 0x00000000FFFFFFFF;
+      _BitScanReverse(&leading_zero, low);
+    }
+#  endif
     int32_t pow2ceiling = 64 - (63 - leading_zero); /* smallest power of 2 containing value */
 #else
     int32_t pow2ceiling = 64 - __builtin_clzll(value | h->sub_bucket_mask); /* smallest power of 2 containing value */