gnu: Add python-gdstk.

* gnu/packages/electronics.scm (python-gdstk): New variable

Change-Id: Ie6bf8e37106020bc723160347a9d111eb8bbc450

gnu/packages/electronics.scm

@@ -2217,6 +2217,14 @@ Chip toolkit.")
         (base32 "0q07g7h613yqszgs49vbnran3pz6yayc0hyisdnp4fi60cyzsz1l"))
        (file-name (git-file-name name version))))
     (build-system cmake-build-system)
+    (arguments
+     (list
+      #:phases
+      #~(modify-phases %standard-phases
+          (add-before 'check 'build-examples
+            (lambda* (#:key tests? #:allow-other-keys)
+              (when tests?
+                (invoke "make" "examples")))))))
     (inputs (list zlib qhull))
     (home-page "https://heitzmann.github.io/gdstk/")
     (synopsis "Library for creation and manipulation of GDSII files")