EdkShellPkg: Add Aarch64 support

* Update the EFI Shell patch to use SVN rev 64 (was rev 61)
* Modify build system to enable compilation targeting Aarch64 platform.
* Modify patch to apply on EdkShell sources to add support for Aarch64.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <olivier.martin@arm.com>



git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14699 6f19259b-4bc3-4df7-8a09-765794883524
diff --git a/EdkShellPkg/ReadMe.txt b/EdkShellPkg/ReadMe.txt
index c05ec8c..b6ce6f5 100644
--- a/EdkShellPkg/ReadMe.txt
+++ b/EdkShellPkg/ReadMe.txt
@@ -15,8 +15,8 @@
    To use this file, execute the following command under workspace to build EDK Shell source:
    build -a IA32 -a X64 -a IPF -p EdkShellPkg\EdkShellPkg.dsc
    
-4. If you need to compile for GCC or ARM you will need to apply ShellR61.patch.
-   cd $(WORKSPACE)/Shell and execute patch -p1 < $(WORKSPACE)/EdkShellPkg/ShellR61.patch.
+4. If you need to compile for GCC or ARM you will need to apply ShellR64.patch.
+   cd $(WORKSPACE)/Shell and execute patch -p0 < $(WORKSPACE)/EdkShellPkg/ShellR64.patch.
    If you are using a case sensative file system there are a few case bugs that patch 
    would not fix. Just fix the case of the file to match its usage and you should be 
    able to compile.