MDL-44357 theme: Allow core to compile LESS in PHP

lib/lessphp/Less.php.combine

@@ -0,0 +1,17 @@
+
+./Parser.php
+./Colors.php
+./Environment.php
+./Functions.php
+./Mime.php
+./Tree.php
+./Output.php
+./Visitor.php
+./VisitorReplacing.php
+./Configurable.php
+./Tree
+./Visitor
+./Exception/Parser.php
+./Exception/
+./Output
+./SourceMap