[libcxx][test] Fix fs::proximate tests on platforms where /net exists.

Following Eric's patch.

llvm-svn: 329199

libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.proximate/proximate.pass.cpp

@@ -87,7 +87,7 @@ TEST_CASE(basic_test) {
       {"a", "a", "."},
       {"a/b", "a/b", "."},
       {"a/b/c/", "a/b/c/", "."},
-      {"//net/a/b", "//net/a/b", "."},
+      {"//foo/a/b", "//foo/a/b", "."},
       {"/a/d", "/a/b/c", "../../d"},
       {"/a/b/c", "/a/d", "../b/c"},
       {"a/b/c", "a", "b/c"},