add ".def" generation for MSVC build

racket/src/worksp/build.bat

@@ -63,3 +63,6 @@ if errorlevel 1 exit /B 1
 
 ..\..\racket -G %BUILD_CONFIG% -N "raco" %SELF_RACKET_FLAGS% -l- setup %PLT_SETUP_OPTIONS%
 if errorlevel 1 exit /B 1
+
+..\..\racket -G ..\%BUILD_CONFIG% -u gendef.rkt
+if errorlevel 1 exit /B 1

racket/src/worksp/gendef.rkt

@@ -0,0 +1,30 @@
+;; Generate ".def" files for installed DLLs
+#lang racket/base
+(require racket/system)
+
+(define lib-dir (build-path 'up 'up "lib"))
+
+(define (gen-one name)
+  (define f (build-path lib-dir (format "~axxxxxxx.dll" name)))
+  (when (file-exists? f)
+    (define s (open-output-bytes))
+    (parameterize ([current-output-port s])
+      (system (format "dumpbin /exports ~a" f)))
+    (define i (open-input-bytes (get-output-bytes s)))
+    (regexp-match #rx"ordinal +hint +RVA +name" i)
+    (call-with-output-file*
+     (build-path lib-dir (format "~axxxxxxx.def" name))
+     #:exists 'truncate
+     (lambda (o)
+      (fprintf o "EXPORTS\n")
+      (for ([l (in-lines i)])
+        (define m (regexp-match
+		   #rx"([0-9]+) +(?:[0-9A-Fa-f]+) +(?:[0-9A-Fa-f]+) +([_A-Za-z][_A-Za-z0-9]*) +="
+		   l))
+	(when m
+	  (fprintf o "    ~a @~a\n" (caddr m) (cadr m))))))))
+
+(gen-one "libmzgc")
+(gen-one "libracket")
+(gen-one "libracket3m")
+