Rename PQtraceSetFlags() to PQsetTraceFlags().

We have a dozen PQset*() functions.  PQresultSetInstanceData() and this
were the libpq setter functions having a different word order.  Adopt
the majority word order.

Reviewed by Alvaro Herrera and Robert Haas, though this choice of name
was not unanimous.

Discussion: https://postgr.es/m/20210605060555.GA216695@rfd.leadboat.com

doc/src/sgml/libpq.sgml

@@ -6533,14 +6533,14 @@ void PQtrace(PGconn *conn, FILE *stream);
     </listitem>
    </varlistentry>
 
-   <varlistentry id="libpq-PQtraceSetFlags">
-    <term><function>PQtraceSetFlags</function><indexterm><primary>PQtraceSetFlags</primary></indexterm></term>
+   <varlistentry id="libpq-PQsetTraceFlags">
+    <term><function>PQsetTraceFlags</function><indexterm><primary>PQtraceSetFlags</primary></indexterm></term>
 
     <listitem>
      <para>
       Controls the tracing behavior of client/server communication.
 <synopsis>
-void PQtraceSetFlags(PGconn *conn, int flags);
+void PQsetTraceFlags(PGconn *conn, int flags);
 </synopsis>
      </para>
 

src/interfaces/libpq/exports.txt

@@ -183,5 +183,5 @@ PQenterPipelineMode       180
 PQexitPipelineMode        181
 PQpipelineSync            182
 PQpipelineStatus          183
-PQtraceSetFlags           184
+PQsetTraceFlags           184
 PQmblenBounded              185

src/interfaces/libpq/fe-trace.c

@@ -61,7 +61,7 @@ PQuntrace(PGconn *conn)
 
 /* Set flags for current tracing session */
 void
-PQtraceSetFlags(PGconn *conn, int flags)
+PQsetTraceFlags(PGconn *conn, int flags)
 {
 	if (conn == NULL)
 		return;

src/interfaces/libpq/libpq-fe.h

@@ -403,7 +403,7 @@ extern void PQuntrace(PGconn *conn);
 #define PQTRACE_SUPPRESS_TIMESTAMPS		(1<<0)
 /* redact portions of some messages, for testing frameworks */
 #define PQTRACE_REGRESS_MODE			(1<<1)
-extern void PQtraceSetFlags(PGconn *conn, int flags);
+extern void PQsetTraceFlags(PGconn *conn, int flags);
 
 /* === in fe-exec.c === */
 

src/test/modules/libpq_pipeline/libpq_pipeline.c

@@ -1326,7 +1326,7 @@ main(int argc, char **argv)
 		setvbuf(trace, NULL, PG_IOLBF, 0);
 
 		PQtrace(conn, trace);
-		PQtraceSetFlags(conn,
+		PQsetTraceFlags(conn,
 						PQTRACE_SUPPRESS_TIMESTAMPS | PQTRACE_REGRESS_MODE);
 	}