Fix socket buffer timeouts precision using the new sbintime_t KPI instead
of relying on the tvtohz() workaround. The latter has been introduced
lately by jhb@ (r254699) in order to have a fix that can be backported
to STABLE.

Reported by:	Vitja Makarov <vitja.makarov at gmail dot com>
Reviewed by:	jhb (earlier version)
Conform to style(9).  No functional changes.

sys/x86/xen/hvm.c:
	Do not rely on implicit conversion to boolean in expressions
	(e.g. use "if (rc != 0)" instead of "if (rc)".

	Line continuations for functions are indented an additional
	4 spaces.

	Insert an empty line if the function has no local variables.

	Prefer separate initializtion statements to initialzing
	local variables in their declaration.

	Braces that are not necessary may be left out.

MFC after:	2 weeks