[wasm] Increase maximum wasm code space to 512 MB

On all architectures except for arm64 (which has a limit of 128 MB), we
increase the maximum wasm code space from 256 MB to 512 MB. This
generally allows for bigger WebAssembly modules and tolerates the code
size increase because of Liftoff.

R=titzer@chromium.org

Bug: chromium:840292, v8:6600
Change-Id: I999cc0c96740ad3da15cc70114d7835354d67fbf
Reviewed-on: https://chromium-review.googlesource.com/1160702Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54890}

src/globals.h

@@ -157,7 +157,7 @@ constexpr int kDoubleSizeLog2 = 3;
 // ARM64 only supports direct calls within a 128 MB range.
 constexpr size_t kMaxWasmCodeMemory = 128 * MB;
 #else
-constexpr size_t kMaxWasmCodeMemory = 256 * MB;
+constexpr size_t kMaxWasmCodeMemory = 512 * MB;
 #endif
 
 #if V8_HOST_ARCH_64_BIT