Kernel: Build UBSanitizer.cpp in aarch64 builds

All these symbols will be needed once we build MiniStdLib.cpp.

Kernel/Prekernel/CMakeLists.txt

@@ -1,4 +1,5 @@
 set(SOURCES
+    UBSanitizer.cpp
 )
 if ("${SERENITY_ARCH}" STREQUAL "aarch64")
     set(SOURCES
@@ -12,7 +13,6 @@ else()
         Arch/x86/boot.S
         Arch/x86/multiboot.S
         # FIXME: Eventually, some of these should build on aarch64 too.
-        UBSanitizer.cpp
         init.cpp
         ../MiniStdLib.cpp
         ../../Userland/Libraries/LibELF/Relocation.cpp

Kernel/Prekernel/UBSanitizer.cpp

@@ -15,7 +15,11 @@ extern "C" {
 
 static void print_location(const SourceLocation&)
 {
+#if ARCH(I386) || ARCH(X86_64)
     asm volatile("cli; hlt");
+#else
+    for (;;) { }
+#endif
 }
 
 void __ubsan_handle_load_invalid_value(const InvalidValueData&, ValueHandle) __attribute__((used));