Move generic or OS function declarations to qemu-common.h

Move generic or OS related function declarations and macro
TFR to qemu-common.h.

Move win32 include directives to qemu-os-win32.h. While moving,
also add #include <winsock2.h> to fix a recent mingw32
build breakage.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/qemu-os-win32.h b/qemu-os-win32.h
index 1a07e5e..ed2753d 100644
--- a/qemu-os-win32.h
+++ b/qemu-os-win32.h
@@ -26,6 +26,9 @@
 #ifndef QEMU_OS_WIN32_H
 #define QEMU_OS_WIN32_H
 
+#include <windows.h>
+#include <winsock2.h>
+
 /* Polling handling */
 
 /* return TRUE if no sleep should be done afterwards */