Kernel: Add KSyms.cpp to the aarch64 build

This is the first step in making dump_backtrace() work.

Kernel/CMakeLists.txt

@@ -426,6 +426,7 @@ else()
         # Files from base Kernel
         Heap/kmalloc.cpp
         MiniStdLib.cpp
+        KSyms.cpp
 
         Memory/AddressSpace.cpp
         Memory/AnonymousVMObject.cpp