To ensure libiconv can be found by Guix, we need to link the library.

--- a/setup.py
+++ b/setup.py
@@ -109,9 +109,7 @@ if os.name == 'nt':
 else:
     libraries.extend(["m", "z"])
     _platform = sys.platform
-    # Mac and ubuntu: iconv needs to be linked statically
-    if _platform.lower().startswith("darwin") or (is_ubuntu() and is_python_lt_14()):
-        libraries.append("iconv")
+    libraries.append("iconv")
 
 # Extensions
 sources.sort()