Meson: Make spacing and #include ordering a bit more consistent

Not 100%, but a step forward.

Change-Id: I6957edbd24c1652b228a96a68424b857603aae45
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/mesonprojectmanager/project/buildoptions/optionsmodel/arrayoptionlineedit.cpp

@@ -24,8 +24,10 @@
 ****************************************************************************/
 
 #include "arrayoptionlineedit.h"
+
 namespace MesonProjectManager {
 namespace Internal {
+
 ArrayOptionLineEdit::ArrayOptionLineEdit(QWidget *parent)
     : QPlainTextEdit(parent)
 {
@@ -84,5 +86,6 @@ void RegexHighlighter::highlightBlock(const QString &text)
         }
     }
 }
+
 } // namespace Internal
 } // namespace MesonProjectManager