BaseTools: Copy PACKED definition from MdePkg Base.h

BaseTools: Copy PACKED definition from MdePkg Base.h

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2938

MdePkg Acpi10.h definition depends on PACKED.
When structure PCD refers to Acpi10.h, build will fail,
because PACKED definition is missing in BaseTools BaseTypes.h.

C source tools include BaseTools BaseTypes.h. They don't include MdePkg Base.h.
When C source tools include MdePkg Acpi10.h, they also need PACKED definition.
So, add PACKED definition into BaseTools BaseTypes.h.

Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Yuwei Chen <yuwei.chen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Signed-off-by: Liming Gao <gaoliming@byosoft.com.cn>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>
Tested-by: Garrett Kirkendall <garrett.kirkendall@amd.com>