Avoid unportable usage of sscanf(UINT64_FORMAT).

On Mingw, it seems that scanf() doesn't necessarily accept the same format
codes that printf() does, and in particular it may fail to recognize %llu
even though printf() does.  Since configure only probes printf() behavior
while setting up the INT64_FORMAT macros, this means it's unsafe to use
those macros with scanf().  We had only one instance of such a coding
pattern, in contrib/pg_stat_statements, so change that code to avoid
the problem.

Per buildfarm warnings.  Back-patch to 9.0 where the troublesome code
was introduced.

Michael Paquier

contrib/pg_stat_statements/pg_stat_statements.c

@@ -962,7 +962,7 @@ pgss_ProcessUtility(Node *parsetree, const char *queryString,
 	{
 		instr_time	start;
 		instr_time	duration;
-		uint64		rows = 0;
+		uint64		rows;
 		BufferUsage bufusage_start,
 					bufusage;
 		uint32		queryId;
@@ -995,7 +995,15 @@ pgss_ProcessUtility(Node *parsetree, const char *queryString,
 
 		/* parse command tag to retrieve the number of affected rows. */
 		if (completionTag &&
-			sscanf(completionTag, "COPY " UINT64_FORMAT, &rows) != 1)
+			strncmp(completionTag, "COPY ", 5) == 0)
+		{
+#ifdef HAVE_STRTOULL
+			rows = strtoull(completionTag + 5, NULL, 10);
+#else
+			rows = strtoul(completionTag + 5, NULL, 10);
+#endif
+		}
+		else
 			rows = 0;
 
 		/* calc differences of buffer counters. */