From libc manual for vsnprintf:
The functions vprintf(), vfprintf(), vsprintf(), vsnprintf()
are equivalent to the functions printf(), fprintf(), sprintf(), snprintf(),
respectively, except that they are called with a va_list instead of a
variable number of arguments. These functions do not call the va_end macro.
Because they invoke the va_arg macro, the value of ap is undefined after the call.
We need to allocate/end new va_list for each vsnprintf.
Change-Id: I66ec058033be1cb918e7b2bc84ca546800da226b
Signed-off-by: Fengwei Yin <fengwei.yin@intel.com>
