refactored transformation: added folders for each transformation

src/DirectiveProcessing/spf_directive_preproc.cpp

@@ -1,4 +1,4 @@
-#include "../Utils/leak_detector.h"
+#include "leak_detector.h"
 
 #include <cstdio>
 #include <cstdlib>
@@ -18,7 +18,7 @@
 #include "../Utils/SgUtils.h"
 #include "../Utils/errors.h"
 #include "directive_parser.h"
-#include "../ExpressionTransform/expr_transform.h"
+#include "expr_transform.h"
 #include "../LoopAnalyzer/loop_analyzer.h"
 #include "../DirectiveProcessing/directive_omp_parser.h"