Updated included headers to support compilation on Windows (using Visual C++)

- most of posix related functions and constants in unistd.h can be
  found in io.h in Visual C++
- introduced src/compat/msvc.h to adjust for compiler differences (and
  avoid updating code with #ifdef blocks for Windows support)
- removed some included headers that are not needed (both on Unix and
  Windows builds)

src/actions/transformations/html_entity_decode.cc

@@ -27,6 +27,10 @@
 #include "modsecurity/transaction.h"
 #include "src/actions/transformations/transformation.h"
 
+#ifdef WIN32
+#include "src/compat/msvc.h"
+#endif
+
 
 namespace modsecurity {
 namespace actions {

src/actions/transformations/lower_case.cc

@@ -17,6 +17,7 @@
 
 #include <algorithm>
 #include <string>
+#include <locale>
 
 #include "modsecurity/transaction.h"
 #include "src/actions/transformations/transformation.h"

src/actions/transformations/upper_case.cc

@@ -17,6 +17,7 @@
 
 #include <algorithm>
 #include <string>
+#include <locale>
 
 #include "modsecurity/transaction.h"
 #include "src/actions/transformations/transformation.h"