gnu: node-bootstrap: Remove riscv64-linux from supported-systems.

* gnu/packages/node.scm (node-bootstrap)[supported-systems]: New field.
(node-lts)[supported-system]: Restore the default.

Change-Id: Ia2eb1b18298e6bdb088b3d9d8fa4c395b690253f

gnu/packages/node.scm

@@ -342,6 +342,7 @@ for easily building fast, scalable network applications.  Node.js uses an
 event-driven, non-blocking I/O model that makes it lightweight and efficient,
 perfect for data-intensive real-time applications that run across distributed
 devices.")
+    (supported-systems (delete "riscv64-linux" %supported-systems))
     (home-page "https://nodejs.org/")
     (license license:expat)
     (properties '((max-silent-time . 7200)   ;2h, needed on ARM
@@ -990,6 +991,7 @@ fi"
            `(,nghttp2 "lib")
            openssl
            zlib))
+    (supported-systems %supported-systems)
     (properties (alist-delete 'hidden? (package-properties node-bootstrap)))))
 
 (define-public node node-lts)