Problem
=======
A large number (400) of C4101 warnings are generated when compiling the
generated file plugin\group_replication\libmysqlgcs\xdr_gen\xcom_vp_xdr.c

Solution
========
As the xcom_vp_xdr.c is generated, it is not easy to modify its contents
to prevent the compiler warning from being generated. Instead, we modify
the MSVC compiler flags to suppress the C4101 warning when compiling the
generated source file.

Change-Id: I5bb68551ad877a99b08123747b382c21b04e3654