textproc/kdiff3: fix output of merged file

Fix spurious newlines and missing newline at the end of file.

Upstream report:	https://bugs.kde.org/show_bug.cgi?id=437570
Upstream merge request:	https://invent.kde.org/sdk/kdiff3/-/merge_requests/31

PR:			256606
Reported by:		emaste

textproc/kdiff3/Makefile

@@ -1,5 +1,6 @@
 PORTNAME=	kdiff3
 DISTVERSION=	1.9.2
+PORTREVISION=	1
 CATEGORIES=	textproc kde
 MASTER_SITES=	KDE/stable/${PORTNAME}
 

textproc/kdiff3/files/patch-src_mergeresultwindow.cpp

@@ -0,0 +1,50 @@
+See https://invent.kde.org/sdk/kdiff3/-/merge_requests/31
+
+When writing out files, don't treat removed lines as real lines,
+and append a newline to the whole output file.
+--- src/mergeresultwindow.cpp.orig	2021-05-17 17:26:58 UTC
++++ src/mergeresultwindow.cpp
+@@ -2964,6 +2964,9 @@ bool MergeResultWindow::saveDocument(const QString& fi
+         textOutStream.setGenerateByteOrderMark(true); // Only for UTF-16
+     textOutStream.setCodec(pEncoding);
+ 
++    // Determine the line feed for this file
++    const QString lineFeed(eLineEndStyle == eLineEndStyleDos ? QString("\r\n") : QString("\n"));
++
+     int line = 0;
+     MergeLineList::iterator mlIt = m_mergeLineList.begin();
+     for(mlIt = m_mergeLineList.begin(); mlIt != m_mergeLineList.end(); ++mlIt)
+@@ -2976,18 +2979,14 @@ bool MergeResultWindow::saveDocument(const QString& fi
+ 
+             if(mel.isEditableText())
+             {
+-                QString str = mel.getString(m_pldA, m_pldB, m_pldC);
++                const QString str = mel.getString(m_pldA, m_pldB, m_pldC);
+ 
+-                if(line > 0) // Prepend line feed, but not for first line
++                if(line > 0 && !mel.isRemoved())
+                 {
+-                    if(eLineEndStyle == eLineEndStyleDos)
+-                    {
+-                        str.prepend("\r\n");
+-                    }
+-                    else
+-                    {
+-                        str.prepend("\n");
+-                    }
++                    // Put line feed between lines, but not for the first line
++                    // or between lines that have been removed (because there
++                    // isn't a line there).
++                    textOutStream << lineFeed;
+                 }
+ 
+                 textOutStream << str;
+@@ -2995,6 +2994,8 @@ bool MergeResultWindow::saveDocument(const QString& fi
+             }
+         }
+     }
++    // At the end of the stream, needs a newline
++    textOutStream << lineFeed;
+     textOutStream.flush();
+     bool bSuccess = file.writeFile(dataArray.data(), dataArray.size());
+     if(!bSuccess)