boot_time() returns incorrect value on XP

[xiaolingbao]

Build _pswindows.pyd with _WIN32_WINNT set to '0x501' and PSAPI_VERSION=1, and run:

c:\window> python -c "import psutil; print psutil.boot_time()"
4.74414813e+18

Cause:
uptime is defined as double with the above settings (

psutil/psutil/_psutil_windows.c

Line 216 in dd19ba7

double uptime;

), Py_BuildValue() later on expects either ULONGLONG or LONGLONG. There is memory layout mismatch between the expected value format and the supplied.

This is a regression as the previous version uses double in both places.

[giampaolo]

Can you submit a PR?