This patch fixes a compiler warning when cross-build:

qga/service-win32.c: In function 'printf_win_error':
qga/service-win32.c:32:5: warning: format '%d' expects argument of type 'int',
                          but argument 3 has type 'DWORD' [-Wformat]
Signed-off-by: NLei Li <lilei@linux.vnet.ibm.com>
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>