advice: pass varargs to strbuf_vaddf, not strbuf_addf
The advise() function takes a variable number of arguments and converts them into a va_list object to pass to strbuf for handling. However, we accidentally called strbuf_addf (that takes a variable number of arguments) instead of strbuf_vaddf (that takes a va_list).
This bug dates back to v184.108.40.206-1-g23cb5bf, but we never noticed because none of the current callers passes a string with a format specifier in it. And the compiler did not notice because the format string is not available at compile time.
Signed-off-by: Jeff King <email@example.com> Signed-off-by: Junio C Hamano <firstname.lastname@example.org>