[babl/wip/msvc] babl/babl-extension.c: Don't include unistd.h on Windows

[Chun-wei Fan <fanchunwei src gnome org>]

commit 39e3bb173c096c9ee01e2c2950c1e58fd4dd14da
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Mon Jan 20 17:08:46 2020 +0800

    babl/babl-extension.c: Don't include unistd.h on Windows
    
    It is not universally available on Windows...

 babl/babl-extension.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/babl/babl-extension.c b/babl/babl-extension.c
index 41edb8e9b..0e66a108c 100644
--- a/babl/babl-extension.c
+++ b/babl/babl-extension.c
@@ -126,7 +126,10 @@ babl_extension_deinit (void)
 #include <dirent.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+
+#ifndef WIN32
 #include <unistd.h>
+#endif
 
 #ifdef HAVE_DLFCN_H
 #ifndef WIN32