uefi-sct/SctPkg: Fix build with latest EDK2
uefi-sct/SctPkg: Fix build with latest EDK2

Update the SctPkg build.sh script to work with latest EDK2, without
depending on UDK2017. Changes include:

 - Allowing GCC versions 5+
 - Refactoring WORKSPACE based on the new EDK2 stuructre
   (SctPkg is treated as another PACKAGES_PATH component, not a package
   in the Edk2 folder itself)
 - Remove unnecessary EdkCompatibilityPkg reference

This patch depends on the change in https://edk2.groups.io/g/devel/message/60407

Signed-off-by: Samer El-Haj-Mahmoud <5dc15713d5080867bcb7fca77831476f4d6bd494@arm.com>
Reviewed-by: G Edhaya Chandran<ac011554eec6bd974d9badfa44ab85dfe3150932@arm.com>

tianocore/edk2-test,tianocore/edk2-test,tianocore/edk2-test