test-paths.t: enable for Windows using #if

If the no-msys exit at the beginning is removed, the test fails on Windows with
MSYS with:

  --- C:\Users\adi\hgrepos\hg-main\tests\test-paths.t
  +++ C:\Users\adi\hgrepos\hg-main\tests\test-paths.t.err
  @@ -24,7 +24,7 @@
     expand = $TESTTMP/a/foo/bar (glob)
     $ SOMETHING=/foo hg paths
     dupe = $TESTTMP/b (glob)
  -  expand = /foo/bar
  +  expand = c:/MinGW/msys/1.0/foo/bar
     $ hg paths -q
     dupe
     expand

caused by http://www.mingw.org/wiki/Posix_path_conversion .

tests/test-paths.t

@@ -1,5 +1,3 b''
-  $ "$TESTDIR/hghave" no-msys || exit 80 # MSYS will translate /foo/bar as if it was a real file path
-
   $ hg init a
   $ hg clone a b
   updating to branch default
@@ -24,9 +22,15 b''
   $ SOMETHING=foo hg paths
   dupe = $TESTTMP/b (glob)
   expand = $TESTTMP/a/foo/bar (glob)
+#if msys
+  $ SOMETHING=//foo hg paths
+  dupe = $TESTTMP/b (glob)
+  expand = /foo/bar
+#else
   $ SOMETHING=/foo hg paths
   dupe = $TESTTMP/b (glob)
   expand = /foo/bar
+#endif
   $ hg paths -q
   dupe
   expand