gnu: Add missing module import to (gnu packages ldc).

This is a followup to commit e44b5112.

* gnu/packages/ldc.scm: Import (gnu packages python).

gnu/packages/ldc.scm

@@ -29,6 +29,7 @@ (define-module (gnu packages ldc)
   #:use-module (gnu packages compression)
   #:use-module (gnu packages libedit)
   #:use-module (gnu packages llvm)
+  #:use-module (gnu packages python)
   #:use-module (gnu packages textutils)
   #:use-module (gnu packages zip))