Fix linux build by making windows changes conditional (#13)

Co-authored-by: Bodo Graumann <mail@bodograumann.de>

Author: StanFromIreland

setup.py

@@ -1,4 +1,12 @@
 from setuptools import setup, Extension
+import sys
+
+# On Linux, iconv is part of glibc and doesn't need separate linkage
+# Otherwise, link against libiconv
+if sys.platform.startswith('linux'):
+    libraries = []
+else:
+    libraries = ["iconv"]
 
 setup(
     name="python-iconv",
@@ -15,5 +23,5 @@
 all iconv-provided encodings.
 """,
     py_modules=["iconvcodec"],
-    ext_modules=[Extension("iconv", sources=["iconvmodule.c"], libraries=["iconv"])],
+    ext_modules=[Extension("iconv", sources=["iconvmodule.c"], libraries=libraries)],
 )