Fix incorrect quoting of $ sign

Author: fangerer

graalpython/com.oracle.graal.python.cext/setup.py

@@ -59,7 +59,7 @@
 
 verbosity = '--verbose' if sys.flags.verbose else '--quiet'
 darwin_native = sys.platform == "darwin" and __graalpython__.platform_id == "native"
-relative_rpath = "@loader_path" if darwin_native else r"\$ORIGIN"
+relative_rpath = "@loader_path" if darwin_native else r"$ORIGIN"
 so_ext = get_config_var("EXT_SUFFIX")
 SOABI = get_config_var("SOABI")
 is_managed = 'managed' in SOABI