Disable build of Python bindings, which requires the sipconfig module.

Signed-off-by: Simon Dawson <spdawson@gmail.com>

diff -Nurp a/Makefile.am b/Makefile.am
--- a/Makefile.am	2008-11-12 01:27:31.000000000 +0000
+++ b/Makefile.am	2013-04-16 09:41:13.476002178 +0100
@@ -1,4 +1,4 @@
-SUBDIRS=src doc examples sip
+SUBDIRS=src doc examples
 
 EXTRA_DIST = doxygen.conf.in Makefile.dist libserial.spec libserial.pc
 
diff -Nurp a/Makefile.in b/Makefile.in
--- a/Makefile.in	2008-11-12 01:28:14.000000000 +0000
+++ b/Makefile.in	2013-04-16 09:41:05.628013626 +0100
@@ -197,7 +197,7 @@ sysconfdir = @sysconfdir@
 target_alias = @target_alias@
 top_builddir = @top_builddir@
 top_srcdir = @top_srcdir@
-SUBDIRS = src doc examples sip
+SUBDIRS = src doc examples
 EXTRA_DIST = doxygen.conf.in Makefile.dist libserial.spec libserial.pc
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = libserial.pc