Revamp tar_getcwd/normalize_filename stuff.

The changes are based on the discussion with Nathan.

* src/common.h (normalize_filename): Take two arguments. All
callers updated.
(tar_getcwd): Replaced with ..
(tar_getcdpath): New proto.
* src/misc.c (normalize_filename): Take two arguments.
(chdir_arg): Populate cwd along with creating the
structure.
(tar_getcwd): Removed.
(tar_getcdpath): New function.

* tests/incr09.at: New test case.
* tests/Makefile.am: Add new tests.
* tests/testsuite.at: Likewise.

tests/Makefile.am

@@ -113,6 +113,7 @@ TESTSUITE_AT = \
  incr06.at\
  incr07.at\
  incr08.at\
+ incr09.at\
  indexfile.at\
  ignfail.at\
  label01.at\

tests/incr09.at

@@ -0,0 +1,59 @@
+# Process this file with autom4te to create testsuite. -*- Autotest -*-
+# Test suite for GNU tar.
+# Copyright 2013 Free Software Foundation, Inc.
+#
+# GNU tar is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# GNU tar is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+AT_SETUP([incremental with alternating -C])
+AT_KEYWORDS([incremental create incr09])
+
+AT_TAR_CHECK([
+AT_SORT_PREREQ
+mkdir foo bar middle
+echo foo/foo_file > foo/foo_file
+echo bar/bar_file > bar/bar_file
+echo middle/file > middle/middle_file
+decho A
+tar -cvf foo.tar --incremental -C foo . -C `pwd` middle  -C bar .
+
+rm foo.tar
+>toplevel_file
+decho B
+tar -cvf foo.tar --incremental -C foo . -C `pwd` toplevel_file  -C bar .
+],
+[0],
+[A
+./
+./
+middle/
+./bar_file
+./foo_file
+middle/middle_file
+B
+./
+./
+toplevel_file
+./bar_file
+./foo_file
+],
+[A
+tar: .: Directory is new
+tar: middle: Directory is new
+tar: .: Directory is new
+B
+tar: .: Directory is new
+tar: .: Directory is new
+],[],[],[gnu])
+
+AT_CLEANUP

tests/testsuite.at

@@ -298,6 +298,7 @@ m4_include([incr05.at])
 m4_include([incr06.at])
 m4_include([incr07.at])
 m4_include([incr08.at])
+m4_include([incr09.at])
 
 AT_BANNER([Files removed while archiving])
 m4_include([filerem01.at])