Use angle brackets (<>) rather than quotes ("") for the include
directives in our .h files. This should avoid some potentially nasty
surprises for Winelib apps.

diff --git a/include/mapicode.h b/include/mapicode.h
index 57346d6..c6b7a9d 100644
--- a/include/mapicode.h
+++ b/include/mapicode.h
@@ -21,7 +21,7 @@
 #ifndef MAPICODE_H
 #define MAPICODE_H
 
-#include "winerror.h"
+#include <winerror.h>
 
 #define MAKE_MAPI_SCODE(sev,fac,code) \
     ( (((ULONG)(sev)<<31) | ((ULONG)(fac)<<16) | ((ULONG)(code))) )