Use relative path

Author: mxamin

setup.py

@@ -4,8 +4,9 @@
 
 from build_support.build_ext import build_ext
 
+
 src_root = Path(__file__).parent / 'src'
-sources = [str(path.absolute()) for path in src_root.rglob('*.c')]
+sources = [str(path.relative_to(Path(__file__).parent)) for path in src_root.rglob('*.c')]
 pyxmlsec = Extension('xmlsec', sources=sources)