BootUp: Clean up elf BootUp code.

 * The file already exsists, otherwise we wouldn't have gotten
   this far in the boot.
 * We have already checked if it's a Wii or GameCube elf,
   besides, it's too late to change our minds now anyway.
 * On Wii - Don't call EmulatedBS2, it can never succeed as
   it knows nothing about booting elfs. Just call the
   SetupWiiMemory directly if needed.
 * On GameCube - We still call EmulatedBS2_GC, but we stop
   it from running Apploader, which might boot something
   unexpected from the default iso or DVD root folder.
ElfReader: Clean up elf loader code.

 * Don't claim to support any features we don't, like relocation
 * Actually zero-out BSS sections, as memory might not be already
   zeroed.
 * Deleted commented out code.
 * Removed GetPointer, updated to more modern interface methods.
 * Updated pointer types style from "u32 *x" to "u32* x"
IsWiiElf: Optimise inner loop.

Instead of swaping each word of the elf code section(s) looking
for a match to our pattern, we swap the pattern just once (at
compile  time) and test against our swapped pattern.