Revert "No longer check for X11"

For now revert this, on non X11 systems it causes:

FAILURE (KCmdLineArgs):
Application requests for isSet("display") but the "display" option
has never been specified via addCmdLineOptions( ... )

This reverts commit d42ef186c8.

CMakeLists.txt

@@ -36,6 +36,10 @@ find_package(KF5 REQUIRED
     WindowSystem XmlGui
 )
 
+find_package(X11)
+set_package_properties(X11 PROPERTIES TYPE OPTIONAL)
+set(HAVE_X11 ${X11_FOUND})
+
 remove_definitions(-DQT_NO_SIGNALS_SLOTS_KEYWORDS -DQT_NO_CAST_FROM_ASCII)
 add_definitions(-Wno-deprecated-declarations)
 

src/config-konsole.h.cmake

@@ -7,4 +7,6 @@
 /* Defined if on DragonFly BSD */
 #cmakedefine HAVE_OS_DRAGONFLYBSD 1
 
-#define KONSOLE_VERSION "${Konsole_VERSION}"
+#cmakedefine01 HAVE_X11
+
+#define KONSOLE_VERSION "${Konsole_VERSION}"

src/main.cpp

@@ -96,8 +96,9 @@ bool shouldUseNewProcess()
     QStringList qtProblematicOptions;
     qtProblematicOptions << "session" << "name" << "reverse"
                          << "stylesheet" << "graphicssystem";
-    // From X11
+#if HAVE_X11
     qtProblematicOptions << "display" << "visual";
+#endif
     foreach(const QString& option, qtProblematicOptions) {
         if ( qtArgs->isSet(option.toLocal8Bit()) ) {
             return true;
@@ -108,8 +109,9 @@ bool shouldUseNewProcess()
     const KCmdLineArgs* kdeArgs = KCmdLineArgs::parsedArgs("kde");
     QStringList kdeProblematicOptions;
     kdeProblematicOptions << "config" << "style";
-    // From X11
+#if HAVE_X11
     kdeProblematicOptions << "waitforwm";
+#endif
     foreach(const QString& option, kdeProblematicOptions) {
         if ( kdeArgs->isSet(option.toLocal8Bit()) ) {
             return true;