gnu: go-github-com-charmbracelet-x-term: Use delete-all-but.

* gnu/packages/golang-xyz.scm (go-github-com-charmbracelet-x-term)[source]<snippet>:
Delete all but source for the current module.

Change-Id: I7e6577a70d184b26b9707dc0ae7874debc98cb43

gnu/packages/golang-xyz.scm

@@ -3524,7 +3524,19 @@ package provides an API for comparing Golden files.")
                                           #:subdir "term"))))
        (file-name (git-file-name name version))
        (sha256
-        (base32 "1shw55110fnn4xz80wmgr18czmiil6z1j064m90iw8c7j9llfzn5"))))
+        (base32 "1shw55110fnn4xz80wmgr18czmiil6z1j064m90iw8c7j9llfzn5"))
+       (modules '((guix build utils)
+                  (ice-9 ftw)
+                  (srfi srfi-26)))
+       (snippet
+        #~(begin
+            (define (delete-all-but directory . preserve)
+              (with-directory-excursion directory
+                (let* ((pred (negate (cut member <>
+                                          (cons* "." ".." preserve))))
+                       (items (scandir "." pred)))
+                  (for-each (cut delete-file-recursively <>) items))))
+            (delete-all-but "." "term")))))
     (build-system go-build-system)
     (arguments
      (list