BaseTools PeCoffLib: Fix the issue to get RelocationsStripped from TE image
If PE image has no relocation section, and has not set RELOCS_STRIPPED,
after it is converted to TE image, GenFw will set its relocation section
VirtualAddress to non-zero address, and keep Size value as Zero. MdePkg
BasePeCoffLib applied this rule to get RelocationsStripped attribute. But,
it is missing in BaseTools BasePeCoffLib.