Fix failure in mjsunit/wasm/embenchen/box2d on 32-bit architectures that do...

Fix failure in mjsunit/wasm/embenchen/box2d on 32-bit architectures that do not support unaligned access.

This test fails because WasmGraphBuilder::BuildCFuncInstruction allocates
space for doubles using StackSlot turbofan operator, but this space is not
guaranteed to be 8 bytes aligned if SP itself is not 8 bytes aligned (which
is the case on 32-bit architectures).

BUG=mjsunit/wasm/embenchen/box2d

Review-Url: https://codereview.chromium.org/2177863002
Cr-Commit-Position: refs/heads/master@{#38039}

src/wasm/wasm-external-refs.cc

@@ -25,13 +25,21 @@ void f32_ceil_wrapper(float* param) { *param = ceilf(*param); }
 
 void f32_nearest_int_wrapper(float* param) { *param = nearbyintf(*param); }
 
-void f64_trunc_wrapper(double* param) { *param = trunc(*param); }
+void f64_trunc_wrapper(double* param) {
+  WriteDoubleValue(param, trunc(ReadDoubleValue(param)));
+}
 
-void f64_floor_wrapper(double* param) { *param = floor(*param); }
+void f64_floor_wrapper(double* param) {
+  WriteDoubleValue(param, floor(ReadDoubleValue(param)));
+}
 
-void f64_ceil_wrapper(double* param) { *param = ceil(*param); }
+void f64_ceil_wrapper(double* param) {
+  WriteDoubleValue(param, ceil(ReadDoubleValue(param)));
+}
 
-void f64_nearest_int_wrapper(double* param) { *param = nearbyint(*param); }
+void f64_nearest_int_wrapper(double* param) {
+  WriteDoubleValue(param, nearbyint(ReadDoubleValue(param)));
+}
 
 void int64_to_float32_wrapper(int64_t* input, float* output) {
   *output = static_cast<float>(*input);