Waf build not respecting DESTDIR variable

[tridge at samba.org]

Hi Stuart,

 > I attached a patch to fix the location of the external samba python 
 > libraries.

yes, Jelmer noticed the same thing. I removed TOUCH_FILE() a few days
ago:

  http://build.samba.org/?function=diff;tree=samba_4_0_waf;date=1270549646;revision=64594f296ca84c487e5cd7ec5e76153cb3b3ef4a

that fixes the problem with honoring DESTDIR, and also means that 'waf
uninstall' does the right thing.

Cheers, Tridge