Fix conflict when using PostgreSQL 14.

Index: agent/bin/pgut/pgut.h
--- agent/bin/pgut/pgut.h.orig
+++ agent/bin/pgut/pgut.h
@@ -151,7 +151,7 @@ extern void CHECK_FOR_INTERRUPTS(void);
 #define appendStringInfoChar	appendPQExpBufferChar
 #define appendBinaryStringInfo	appendBinaryPQExpBuffer
 
-extern bool appendStringInfoVA(StringInfo str, const char *fmt, va_list args)
+extern bool appendStringInfoVA_(StringInfo str, const char *fmt, va_list args)
 __attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 0)));
 extern int appendStringInfoFile(StringInfo str, FILE *fp);
 extern int appendStringInfoFd(StringInfo str, int fd);
