tests: Solaris cp doesn't support the -T option

The treemanifest tests use the -T option to cp in order to ensure that the
two directories named on the commandline are treated as peers, rather than
the usual behavior when the final argument is a directory.  GNU cp has this
option, but other implementations may not.  Thankfully, there's no pressing
reason to use it.  We can simply copy the contents of the first directory
into the target directory, since we know that the target directory already
exists.

tests/test-treemanifest.t

@@ -541,7 +541,7 b' Verify reports missing dirlog'
   8 integrity errors encountered!
   (first damaged changeset appears to be 0)
   [1]
-  $ cp -rT .hg/store-newcopy .hg/store
+  $ cp -r .hg/store-newcopy/. .hg/store
 
 Verify reports missing dirlog entry
   $ mv -f .hg/store-copy/meta/b/00manifest.* .hg/store/meta/b/
@@ -566,7 +566,7 b' Verify reports missing dirlog entry'
   8 integrity errors encountered!
   (first damaged changeset appears to be 1)
   [1]
-  $ cp -rT .hg/store-newcopy .hg/store
+  $ cp -r .hg/store-newcopy/. .hg/store
 
 Test cloning a treemanifest repo over http.
   $ hg serve -p $HGPORT -d --pid-file=hg.pid --errorlog=errors.log