Kernel: Use a raw VM region for sorting ELF symbols instead of a Vector.

This avoids putting pressure on kmalloc() during backtrace symbolication.
Since we dump backtrace for every process that exits, this is actually a
decent performance improvement for things like GCC that chain a lot of
processes together.

AK/ELF/ELFLoader.h

@@ -4,11 +4,13 @@
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 #include <AK/Vector.h>
-#if defined(KERNEL)
-#    include <Kernel/VirtualAddress.h>
-#endif
 #include <AK/ELF/ELFImage.h>
 
+#ifdef KERNEL
+#include <Kernel/VirtualAddress.h>
+class Region;
+#endif
+
 class ELFLoader {
 public:
     explicit ELFLoader(const byte*);
@@ -50,5 +52,9 @@ private:
         dword address;
         const char* name;
     };
+#ifdef KERNEL
+    mutable RefPtr<Region> m_sorted_symbols_region;
+#else
     mutable Vector<SortedSymbol> m_sorted_symbols;
+#endif
 };