Everywhere: Make the codebase more architecture aware

Author: https://github.com/cqundefine
Commit: 97cc33ca47
Pull-request: https://github.com/SerenityOS/serenity/pull/14651
Reviewed-by: https://github.com/bgianfo ✅
Reviewed-by: https://github.com/linusg

Kernel/Heap/kmalloc.cpp

@@ -20,8 +20,10 @@
 
 #if ARCH(I386)
 static constexpr size_t CHUNK_SIZE = 32;
-#else
+#elif ARCH(X86_64) || ARCH(AARCH64)
 static constexpr size_t CHUNK_SIZE = 64;
+#else
+#    error Unknown architecture
 #endif
 static_assert(is_power_of_two(CHUNK_SIZE));