Don't check for Python with --disable-pywrap option passed

If user passes --disable-pywrap option, then `configure` needlessly still checks for Python, which might result in an error if Python 3 is installed:

$ ./configure --disable-pywrap
checking build system type... x86_64-unknown-linux-gnu
checking host system type... x86_64-unknown-linux-gnu
checking target system type... x86_64-unknown-linux-gnu
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking for a Python interpreter with version >= 2.5... python
checking for python... /usr/bin/python
checking for python version... 3.2
checking for python platform... linux2
checking for python script directory... ${prefix}/lib64/python3.2/site-packages
checking for python extension module directory... ${exec_prefix}/lib64/python3.2/site-packages
checking for swig... /usr/bin/swig
checking for SWIG version... 2.0.4
configure: WARNING: SWIG version >= 1.3.31 is required. You have 2.0.4. You should look at http://www.swig.org
checking for style of include used by make... GNU
checking for gcc... gcc
checking whether the C compiler works... yes
checking for C compiler default output file name... a.out
checking for suffix of executables...
checking whether we are cross compiling... no
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ISO C89... none needed
checking dependency style of gcc... gcc3
checking for python3.2... (cached) /usr/bin/python
checking for a version of Python >= '2.1.0'... File "<string>", line 1
    import sys, string; ver = string.split(sys.version)[0]; print ver >= '2.1.0'
                                                                                                    ^
SyntaxError: invalid syntax
no
configure: error: in `/tmp/ecryptfs-utils-93':
configure: error:
This version of the AC_PYTHON_DEVEL macro
doesn't work properly with versions of Python before
2.1.0. You may need to re-run configure, setting the
variables PYTHON_CPPFLAGS, PYTHON_LDFLAGS, PYTHON_SITE_PKG,
PYTHON_EXTRA_LIBS and PYTHON_EXTRA_LDFLAGS by hand.
Moreover, to disable this check, set PYTHON_NOVERSIONCHECK
to something else than an empty string.

See `config.log' for more details
$