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/variables/time.cc

@@ -30,6 +30,10 @@
 
 #include "modsecurity/transaction.h"
 
+#ifdef WIN32
+#include "src/compat/msvc.h"
+#endif
+
 namespace modsecurity {
 namespace variables {
 

src/variables/time_day.cc

@@ -30,6 +30,10 @@
 
 #include "modsecurity/transaction.h"
 
+#ifdef WIN32
+#include "src/compat/msvc.h"
+#endif
+
 namespace modsecurity {
 namespace variables {
 

src/variables/time_hour.cc

@@ -30,6 +30,10 @@
 
 #include "modsecurity/transaction.h"
 
+#ifdef WIN32
+#include "src/compat/msvc.h"
+#endif
+
 namespace modsecurity {
 namespace variables {
 

src/variables/time_min.cc

@@ -30,6 +30,10 @@
 
 #include "modsecurity/transaction.h"
 
+#ifdef WIN32
+#include "src/compat/msvc.h"
+#endif
+
 namespace modsecurity {
 namespace variables {
 

src/variables/time_mon.cc

@@ -30,6 +30,10 @@
 
 #include "modsecurity/transaction.h"
 
+#ifdef WIN32
+#include "src/compat/msvc.h"
+#endif
+
 namespace modsecurity {
 namespace variables {
 

src/variables/time_sec.cc

@@ -30,6 +30,10 @@
 
 #include "modsecurity/transaction.h"
 
+#ifdef WIN32
+#include "src/compat/msvc.h"
+#endif
+
 namespace modsecurity {
 namespace variables {
 

src/variables/time_wday.cc

@@ -30,6 +30,10 @@
 
 #include "modsecurity/transaction.h"
 
+#ifdef WIN32
+#include "src/compat/msvc.h"
+#endif
+
 namespace modsecurity {
 namespace variables {
 

src/variables/time_year.cc

@@ -30,6 +30,10 @@
 
 #include "modsecurity/transaction.h"
 
+#ifdef WIN32
+#include "src/compat/msvc.h"
+#endif
+
 namespace modsecurity {
 namespace variables {