Revert "- fix memory arena allocation alignment for 32 bit systems."

This reverts commit 23fce56b5e.

This did not do what it was supposed to because of how the block header was created.

src/memarena.cpp

@@ -55,14 +55,13 @@ struct FMemArena::Block
 //
 // RoundPointer
 //
-// Rounds a pointer up to the size of the largest integral type.
+// Rounds a pointer up to a pointer-sized boundary.
 //
 //==========================================================================
 
 static inline void *RoundPointer(void *ptr)
 {
-	const auto roundsize = std::max(sizeof(void*), sizeof(double));
-	return (void *)(((size_t)ptr + roundsize - 1) & ~(roundsize - 1));
+	return (void *)(((size_t)ptr + sizeof(void*) - 1) & ~(sizeof(void*) - 1));
 }
 
 //==========================================================================