VMS: update the properties of symbol search

In this OpenSSL version, we deliver engines with lower case symbol
names.  The DSO symbol finder must be updated to allow for mixed case
symbols or it won't fine them.
Reviewed-by: NRich Salz <rsalz@openssl.org>

crypto/dso/dso_vms.c

@@ -64,6 +64,7 @@
 # include <errno.h>
 # include <rms.h>
 # include <lib$routines.h>
+# include <libfisdef.h>
 # include <stsdef.h>
 # include <descrip.h>
 # include <starlet.h>
@@ -313,11 +314,10 @@ void vms_bind_sym(DSO *dso, const char *symname, void **sym)
 {
     DSO_VMS_INTERNAL *ptr;
     int status;
-# if 0
-    int flags = (1 << 4);       /* LIB$M_FIS_MIXEDCASE, but this symbol isn't
-                                 * defined in VMS older than 7.0 or so */
+# ifdef LIB$M_FIS_MIXEDCASE
+    int flags = LIB$M_FIS_MIXEDCASE;
 # else
-    int flags = 0;
+    int flags = (1 << 4);
 # endif
     struct dsc$descriptor_s symname_dsc;