[compiler] Remove static init for kMinusZeroBits

Chromium has checks which don't like static initializers in binaries,
which fires on effect_control_linearizer.cc. We can remove these by
making kMinusZeroBits (and family) constexpr, but to do this we have to
avoid bit_cast. Instead, set the correct bit pattern manually (thankfully
IEEE 754 0.0 is just zero bits, and -0.0 is 0.0 with a set sign bit).

Change-Id: If1695ff715ad8f821e956757f8f9f7c850895011
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1762009
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63266}

src/compiler/effect-control-linearizer.cc

@@ -3191,9 +3191,14 @@ Node* EffectControlLinearizer::LowerObjectIsSafeInteger(Node* node) {
 
 namespace {
 
-const int64_t kMinusZeroBits = bit_cast<int64_t>(-0.0);
-const int32_t kMinusZeroLoBits = static_cast<int32_t>(kMinusZeroBits);
-const int32_t kMinusZeroHiBits = static_cast<int32_t>(kMinusZeroBits >> 32);
+// There is no (currently) available constexpr version of bit_cast, so we have
+// to make do with constructing the -0.0 bits manually (by setting the sign bit
+// to 1 and everything else to 0).
+// TODO(leszeks): Revisit when upgrading to C++20.
+constexpr int32_t kMinusZeroLoBits = static_cast<int32_t>(0);
+constexpr int32_t kMinusZeroHiBits = static_cast<int32_t>(1) << 31;
+constexpr int64_t kMinusZeroBits =
+    (static_cast<uint64_t>(kMinusZeroHiBits) << 32) | kMinusZeroLoBits;
 
 }  // namespace