Merge "Fix undefined args access for x86_64."

status_t String8::appendFormatV(const char* fmt, va_list args)

{

    int result = NO_ERROR;

    int n = vsnprintf(NULL, 0, fmt, args);

    int n, result = NO_ERROR;

    va_list tmp_args;

    /* args is undefined after vsnprintf.

     * So we need a copy here to avoid the

     * second vsnprintf access undefined args.

     */

    va_copy(tmp_args, args);

    n = vsnprintf(NULL, 0, fmt, tmp_args);

    va_end(tmp_args);

    if (n != 0) {

        size_t oldLength = length();

        char* buf = lockBuffer(oldLength + n);