runtests.pl: support nonewline="yes" in client/stdin sections

tests/FILEFORMAT

@@ -316,8 +316,11 @@ Variables are substituted on the contents of the file as in the <command>
 section.
 </file>
 
-<stdin>
+<stdin [nonewline="yes"]>
 Pass this given data on stdin to the tool.
+
+If 'nonewline' is set, we will cut off the trailing newline of this given data
+before comparing with the one actually received by the client
 </stdin>
 
 </client>

tests/runtests.pl

@@ -3175,6 +3175,13 @@ sub singletest {
 
     if(@stdintest) {
         my $stdinfile="$LOGDIR/stdin-for-$testnum";
+
+        my %hash = getpartattr("client", "stdin");
+        if($hash{'nonewline'}) {
+            # cut off the final newline from the final line of the stdin data
+            chomp($stdintest[$#stdintest]);
+        }
+
         writearray($stdinfile, \@stdintest);
 
         $cmdargs .= " <$stdinfile";