Mark some Filesystem tests as XFAIL for mingw

Symlinks are not supported on mingw.

	* testsuite/27_io/filesystem/operations/read_symlink.cc: XFAIL for
	mingw* targets.
	* testsuite/27_io/filesystem/operations/symlink_status.cc: Likewise.
	* testsuite/experimental/filesystem/operations/read_symlink.cc:
	Likewise.

From-SVN: r261185

libstdc++-v3/ChangeLog

+2018-06-05  Jonathan Wakely  <jwakely@redhat.com>
+
+	* testsuite/27_io/filesystem/operations/read_symlink.cc: XFAIL for
+	mingw* targets.
+	* testsuite/27_io/filesystem/operations/symlink_status.cc: Likewise.
+	* testsuite/experimental/filesystem/operations/read_symlink.cc:
+	Likewise.
+
 2018-06-05  François Dumont  <fdumont@gcc.gnu.org>
 
 	* include/bits/stl_tempbuf.h

libstdc++-v3/testsuite/27_io/filesystem/operations/read_symlink.cc

@@ -18,6 +18,7 @@
 // { dg-options "-std=gnu++17 -lstdc++fs" }
 // { dg-do run { target c++17 } }
 // { dg-require-filesystem-ts "" }
+// { dg-xfail-if "symlinks not supported" { *-*-mingw* } }
 
 #include <filesystem>
 #include <testsuite_hooks.h>

libstdc++-v3/testsuite/27_io/filesystem/operations/symlink_status.cc

@@ -18,6 +18,7 @@
 // { dg-options "-std=gnu++17 -lstdc++fs" }
 // { dg-do run { target c++17 } }
 // { dg-require-filesystem-ts "" }
+// { dg-xfail-if "symlinks not supported" { *-*-mingw* } }
 
 #include <filesystem>
 #include <testsuite_hooks.h>

libstdc++-v3/testsuite/experimental/filesystem/operations/read_symlink.cc

@@ -18,6 +18,7 @@
 // { dg-options "-DUSE_FILESYSTEM_TS -lstdc++fs" }
 // { dg-do run { target c++11 } }
 // { dg-require-filesystem-ts "" }
+// { dg-xfail-if "symlinks not supported" { *-*-mingw* } }
 
 #include <experimental/filesystem>
 #include <testsuite_hooks.h>