BaseTools: Fix private includes for FILE_GUID override

BaseTools: Fix private includes for FILE_GUID override

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=1648

When a module in a DSC file uses a FILE_GUID override in the
module scoped <Defines> section, a copy of the modified INF file
is placed in the Conf/.cache directory.  The check for private
includes uses the INF path to determine if the module is allowed
to use the private includes.  Since the INF path in this case is
not in any package, this check always fails, and no private
include paths are possible.

The fix is to keep both the OriginalPath and the new Path in
the PathClass object, and always use the OriginalPath to see if
the module INF is in the package with private includes.

Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>