Default values for some options apparently not initialised

[Christopher Key]

  Hello,

Whilst trying to debug some strange wireless behaviour, I came across an 
apparent problem in that various option values don't have default values 
set.

A casual glance shows that wpa_strict_rekey and wpa_ptk_rekey members of 
`struct hostapd_bss_config' don't get initialised (see 
hostapd_config_defaults_bss()); there may well be others.  I guess that 
the memory coming back from malloc is zeroed on most platforms, 
defaulting these two options to off, but relying on this seems dangerous 
at best.  This affects 0.7.2.

Kind regards,

Christopher Key