The network filter / snapshot / hooks code introduced some
non-portable pices that broke the win32 build
* configure.ac: Check for net/ethernet.h required by nwfile config
parsing code
* src/conf/nwfilter_conf.c: Define ethernet protocol constants
if net/ethernet.h is missing
* src/util/hooks.c: Disable hooks build on Win32 since it lacks
fork/exec/pipe
* src/util/threads-win32.c: Fix unchecked return value
* tools/virsh.c: Disable SIGPIPE on Win32 since it doesn't exist.
Fix non-portable strftime() formats
This exports 3 basic routines:
- virHookInitialize() initializing the hook support by looking for
scripts availability
- virHookPresent() used to test if there is a hook for a given driver
- virHookCall() which actually calls a synchronous script hook with
the needed parameters
Note that this doesn't expose any public API except for the locations
and arguments passed to the scripts
* src/Makefile.am: add the 2 new files
* src/util/hooks.h src/util/hooks.c: implements the 3 functions
* src/libvirt_private.syms: export the 3 symbols internally
* po/POTFILES.in: add src/util/hooks.c to translatables modules
