plug small memory leak in vfwprintf()

[Stefan Sperling]

ok?

Index: stdio/vfwprintf.c
===================================================================
RCS file: /cvs/src/lib/libc/stdio/vfwprintf.c,v
retrieving revision 1.3
diff -u -p -r1.3 vfwprintf.c
--- stdio/vfwprintf.c   28 Apr 2011 17:38:46 -0000      1.3
+++ stdio/vfwprintf.c   8 May 2011 23:12:00 -0000
@@ -1051,6 +1051,8 @@ overflow:
        ret = -1;
 
 finish:
+       if (convbuf)
+               free(convbuf);
 #ifdef FLOATING_POINT
        if (dtoaresult)
                __freedtoa(dtoaresult);