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/sql.h b/include/sql.h
index 82a7979..c95266c 100644
--- a/include/sql.h
+++ b/include/sql.h
@@ -25,7 +25,7 @@
 #define ODBCVER 0x0351
 #endif
 
-#include "sqltypes.h"
+#include <sqltypes.h>
 
 #ifdef __cplusplus
 extern "C" {