Use new-style system-id macros everywhere possible.  I hope I haven't
missed any.

This compiles and runs on Linux, and external applications have no
problems with it.  The definite test will be to build this on VMS.
diff --git a/crypto/idea/idea_spd.c b/crypto/idea/idea_spd.c
index 301946b..755c7d8 100644
--- a/crypto/idea/idea_spd.c
+++ b/crypto/idea/idea_spd.c
@@ -59,7 +59,7 @@
 /* 11-Sep-92 Andrew Daviel   Support for Silicon Graphics IRIX added */
 /* 06-Apr-92 Luke Brennan    Support for VMS and add extra signal calls */
 
-#if !defined(MSDOS) && (!defined(VMS) || defined(__DECC))
+#if !defined(OPENSSL_SYS_MSDOS) && (!defined(OPENSSL_SYS_VMS) || defined(__DECC))
 #define TIMES
 #endif
 
@@ -82,7 +82,7 @@
    The __TMS macro will show if it was.  If it wasn't defined, we should
    undefine TIMES, since that tells the rest of the program how things
    should be handled.				-- Richard Levitte */
-#if defined(VMS) && defined(__DECC) && !defined(__TMS)
+#if defined(OPENSSL_SYS_VMS_DECC) && !defined(__TMS)
 #undef TIMES
 #endif
 
@@ -289,7 +289,7 @@
 	printf("IDEA raw ecb bytes   per sec = %12.2f (%9.3fuS)\n",b,8.0e6/b);
 	printf("IDEA cbc     bytes   per sec = %12.2f (%9.3fuS)\n",c,8.0e6/c);
 	exit(0);
-#if defined(LINT) || defined(MSDOS)
+#if defined(LINT) || defined(OPENSSL_SYS_MSDOS)
 	return(0);
 #endif
 	}