Add initial visual studio project files and fix the win32 build

Win32 has been rotting for a while. This patch adds vs17 build files
as well as fixing up all build errors that have accumulated.
There are still build warnings but those can be addressed in a followup
patch.

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>

lib/sync.c

@@ -32,11 +32,14 @@
 #include "win32/win32_compat.h"
 #endif
 
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
-#include <unistd.h>
 #include "iscsi.h"
 #include "iscsi-private.h"
 #include "scsi-lowlevel.h"