perf strbuf: Remove redundant va_end() in strbuf_addv()

Each call to va_copy() should have one, and only one, corresponding call
to va_end(). In strbuf_addv() some code paths result in va_end() getting
called multiple times. Remove the superfluous va_end().

Signed-off-by: Mattias Jacobsson <2pi@mok.nu>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sanskriti Sharma <sansharm@redhat.com>
Link: http://lkml.kernel.org/r/20181229141750.16945-1-2pi@mok.nu


Fixes: ce49d843 ("perf strbuf: Match va_{add,copy} with va_end")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>