Add configure test to see whether vsnprintf() is present,

separately from snprintf() --- HPUX, for one, has snprintf but not
vsnprintf.  Fix a minor typo in snprintf.c, too.

Author: tglsfdc

src/backend/port/snprintf.c

@@ -73,7 +73,7 @@ typedef unsigned long long ulong_long;
  * causing nast effects.
  **************************************************************/
 
-/*static char _id[] = "$Id: snprintf.c,v 1.15 1998/12/24 05:28:50 momjian Exp $";*/
+/*static char _id[] = "$Id: snprintf.c,v 1.16 1999/01/17 03:22:49 tgl Exp $";*/
 static char *end;
 static int	SnprfOverflow;
 
@@ -115,7 +115,7 @@ vsnprintf(char *str, size_t count, const char *fmt, va_list args)
 
 static void fmtstr __P((char *value, int ljust, int len, int zpad, int maxwidth));
 
-#ifndef HAVE_LONG_INT_64
+#ifndef HAVE_LONG_LONG_INT_64
 static void fmtnum __P((long value, int base, int dosign, int ljust, int len, int zpad));
 #else
 static void fmtnum __P((long_long value, int base, int dosign, int ljust, int len, int zpad));