KConfig: handle directory symlinks correctly.

Summary:
When /home is a symlink, for instance (as is often the case on FreeBSD),
group deletion would fail because KConfig was comparing non-canonical
paths with canonical-paths:

QDEBUG : KConfigTest::testDelete() Comparing "/home/adridg/.qttest/config/
kconfigtest_subdir/kconfigtest" and "/usr/home/adridg/.qttest/config/
kconfigtest_subdir/kconfigtest"

Test Plan:
mkdir /tmp/derp; ln -s /tmp/derp /tmp/drop
HOME=/tmp/derp bin/kconfigtest testDelete  # Success
HOME=/tmp/drop bin/kconfigtest testDelete  # Fail

Reviewers: adridg, arichardson, apol

Reviewed By: apol

Subscribers: kde-frameworks-devel

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D14927

src/core/kconfig.cpp

@@ -755,10 +755,13 @@ void KConfigPrivate::parseConfigFiles()
                 files = getGlobalFiles();
             } else {
                 if (QDir::isAbsolutePath(fileName)) {
-                    files << fileName;
+                    const QString canonicalFile = QFileInfo(fileName).canonicalFilePath();
+                    if (!canonicalFile.isEmpty()) { // empty if it doesn't exist
+                        files << canonicalFile;
+                    }
                 } else {
                     Q_FOREACH (const QString &f, QStandardPaths::locateAll(resourceType, fileName)) {
-                        files.prepend(f);
+                        files.prepend(QFileInfo(f).canonicalFilePath());
                     }
 
                     // allow fallback to config files bundled in resources

src/core/kconfigini.cpp

@@ -602,7 +602,11 @@ void KConfigIniBackend::setFilePath(const QString &file)
     if (info.exists()) {
         setLocalFilePath(info.canonicalFilePath());
     } else {
-        setLocalFilePath(file);
+        const QString dir = info.dir().canonicalPath();
+        if (!dir.isEmpty())
+            setLocalFilePath(dir + QLatin1Char('/') + info.fileName());
+        else
+            setLocalFilePath(file);
     }
 }