Add alignment feature flag

src/feature_flags.zig

@@ -166,3 +166,5 @@ pub const boundary_based_chunking = true;
 /// https://github.com/mitsuhiko/source-map-rfc/blob/proposals/debug-id/proposals/debug-id.md
 /// https://github.com/source-map/source-map-rfc/pull/20
 pub const source_map_debug_id = true;
+
+pub const alignment_tweak = true;

src/memory_allocator.zig

@@ -79,6 +79,10 @@ const CAllocator = struct {
     }
 
     fn alloc(_: *anyopaque, len: usize, log2_align: u8, _: usize) ?[*]u8 {
+        if (comptime FeatureFlags.alignment_tweak) {
+            return alignedAlloc(len, log2_align);
+        }
+
         const alignment = @as(usize, 1) << @intCast(Allocator.Log2Align, log2_align);
         return alignedAlloc(len, alignment);
     }

src/mimalloc_arena.zig

@@ -230,6 +230,10 @@ pub const Arena = struct {
         var this = bun.cast(*mimalloc.Heap, arena);
         // if (comptime Environment.allow_assert)
         //     ArenaRegistry.assert(.{ .heap = this });
+        if (comptime FeatureFlags.alignment_tweak) {
+            return alignedAlloc(this, len, log2_align);
+        }
+
         const alignment = @as(usize, 1) << @intCast(Allocator.Log2Align, log2_align);
 
         return alignedAlloc(