MdeModulePkg: Source fixes and cleanup for ARMGCC compiles

- Fix EFI_IPv4_ADDRESS usages to use a macro to copy the structure
  instead of direct assignment, to avoid runtime alignment errors.
- Fix a EFI_INPUT_KEY usage in TerminalDxe to use CopyMem()  to copy the
   structure instead of direct assignment, to avoid runtime alignment error.
- Delete excess local variables that are initialized but otherwise unused.
- CompilerIntrinsicsLib library now imported for AARCH64, as well as ARM.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Randy Pawell <randy_pawell@hp.com>
Reviewed-by: Olivier Martin <Olivier.Martin@arm.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>

git-svn-id: svn://svn.code.sf.net/p/edk2/code/trunk/edk2/MdeModulePkg@16471 6f19259b-4bc3-4df7-8a09-765794883524