OvmfPkg: Use toolchain appropriate CpuExceptionHandlerLib

OvmfPkg: Use toolchain appropriate CpuExceptionHandlerLib

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2340

During the SEC phase, use the XCODE5 CpuExceptionHandlerLib library in
place of the standard library when building with the XCODE5 toolchain.
The SEC XCODE5 version of the library performs binary patching and should
only be used when building with the XCODE5 toolchain.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Julien Grall <julien@xen.org>
Cc: Liming Gao <liming.gao@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <0cfdd51deb6d39e08380645f2022b9b76e29f66f.1588856809.git.thomas.lendacky@amd.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>