cs: support raco exe --embed-dlls on Windows

Uses a MemoryModule PR by @DaLynX to fix a setjmp/longjmp
interaction with embedded DLLs.

racket/collects/compiler/embed.rkt

@@ -1563,7 +1563,6 @@
                                            dest
                                            mred?))))))
 	(define embed-dlls? (and (eq? 'windows (cross-system-type))
-                                 (eq? 'racket (cross-system-type 'vm))
 				 (let ([m (assq 'embed-dlls? aux)])
 				   (and m (cdr m)))))
 	(define embedded-dlls-box (and embed-dlls? (box null)))

racket/src/start/MemoryModule.c

@@ -435,6 +435,17 @@ PerformBaseRelocation(PMEMORYMODULE module, ptrdiff_t delta)
     return TRUE;
 }
 
+#ifdef _WIN64
+static BOOL
+RegisterExceptionHandling(PMEMORYMODULE module)
+{
+    PIMAGE_DATA_DIRECTORY pDir = GET_HEADER_DICTIONARY(module, IMAGE_DIRECTORY_ENTRY_EXCEPTION);
+    PIMAGE_RUNTIME_FUNCTION_ENTRY pEntry = (PIMAGE_RUNTIME_FUNCTION_ENTRY)(module->codeBase + pDir->VirtualAddress);
+    UINT count = (pDir->Size / sizeof(IMAGE_RUNTIME_FUNCTION_ENTRY)) - 1;
+    return RtlAddFunctionTable(pEntry, count, (DWORD64)module->codeBase);
+}
+#endif
+
 static BOOL
 BuildImportTable(PMEMORYMODULE module)
 {
@@ -725,6 +736,12 @@ HMEMORYMODULE MemoryLoadLibraryEx(const void *data, size_t size,
         goto error;
     }
 
+#ifdef _WIN64
+    if (!RegisterExceptionHandling(result)) {
+        goto error;
+    }
+#endif
+
     // mark memory pages depending on section headers and release
     // sections that are marked as "discardable"
     if (!FinalizeSections(result)) {