cs: suppress reundant letrec-variable checking

The schmiefy pass already ensures that variables are defined before
use, so skip cpvalid in Chez Scheme. The difference is tiny, though.

pkgs/base/info.rkt

@@ -12,7 +12,7 @@
 
 (define collection 'multi)
 
-(define version "7.6.0.7")
+(define version "7.6.0.8")
 
 (define deps `("racket-lib"
                ["racket" #:version ,version]))

racket/src/cs/compile-file.ss

@@ -2,7 +2,7 @@
 ;; Check to make we're using a build of Chez Scheme
 ;; that has all the features we need.
 (define-values (need-maj need-min need-sub need-dev)
-  (values 9 5 3 15))
+  (values 9 5 3 16))
 
 (unless (guard (x [else #f]) (eval 'scheme-fork-version-number))
   (error 'compile-file

racket/src/cs/linklet.sls

@@ -1269,10 +1269,12 @@
 
   ;; Since the schemify layer inserts `|#%app|` any time the rator of
   ;; an application might not be a procedure, we can avoid redundant
-  ;; checks for other applications by enabling unsafe mode. But do that
+  ;; checks for other applications by enabling unsafe mode. Ditto for
+  ;; potential early reference to `letrec`-bound variables. But do that
   ;; only if we're compiling the primitive layer in unsafe mode.
   (meta-cond
    [(>= (optimize-level) 3)
-    (enable-unsafe-application #t)]
+    (enable-unsafe-application #t)
+    (enable-unsafe-variable-reference #t)]
    [else
     (void)]))

racket/src/racket/src/schvers.h

@@ -16,7 +16,7 @@
 #define MZSCHEME_VERSION_X 7
 #define MZSCHEME_VERSION_Y 6
 #define MZSCHEME_VERSION_Z 0
-#define MZSCHEME_VERSION_W 7
+#define MZSCHEME_VERSION_W 8
 
 /* A level of indirection makes `#` work as needed: */
 #define AS_a_STR_HELPER(x) #x