rtapi_pci.c:  silence -Wint-to-pointer-cast warning

On 32-bit only:

    Compiling realtime halcomp-srcs/hal/components/abs_s32.c
    rtapi/rtapi_pci.c: In function 'pci_enable_device':
    rtapi/rtapi_pci.c:684:34: warning: cast to pointer from integer of
       different size [-Wint-to-pointer-cast]
    rtapi/rtapi_pci.c:685:34: warning: cast to pointer from integer of
       different size [-Wint-to-pointer-cast]
Link -lprotobuf to liblinuxcnc-pb2++.so

    dpkg-shlibdeps: warning: symbol
       _ZN6google8protobuf8internal14WireFormatLite12WriteFixed32EijPN[...]
       used by debian/machinekit/usr/lib/liblinuxcnc-pb2++.so.0 found in
       none of the libraries
    [...]
    dpkg-shlibdeps: warning: 57 other similar warnings have been skipped
        (use -v to see them all)
Remove -lrt from RT_LDFLAGS

    dpkg-shlibdeps: warning: package could avoid a useless dependency if
      [...]/rtapi_app_xenomai-kernel [...]/ulapi-xenomai-kernel.so
      were not linked against librt.so.1 (they use none of the library's
      symbols)
remove -lz from LDFLAGS

    dpkg-shlibdeps: warning: package could avoid a useless dependency if
    debian/machinekit-posix/usr/libexec/linuxcnc/rtapi_app_posix
    was not linked against libz.so.1 (it uses none of the library's symbols)
don't link RT_LDFLAGS to rtapi_app

    dpkg-shlibdeps: warning: package could avoid a useless dependency if
        [...]/rtapi_app_xenomai-kernel [...]/ulapi-xenomai-kernel.so were
	not linked against libnative.so.3 (they use none of the library's
	symbols)
don't link emcweb against libbost_serialization

    dpkg-shlibdeps: warning: package could avoid a useless dependency
        if debian/machinekit/usr/bin/emcweb was not linked against
	libboost_serialization.so.1.49.0 (it uses none of the library's
	symbols)
configure.in:  Leave -lSM and -lICE out of $XAW_LIBS

These aren't used directly and make warnings.

    dpkg-shlibdeps: warning: package could avoid a useless dependency if
        debian/machinekit/usr/bin/xlinuxcnc was not linked against
	libICE.so.6 (it uses none of the library's symbols)
    dpkg-shlibdeps: warning: package could avoid a useless dependency if
        debian/machinekit/usr/bin/xlinuxcnc was not linked against
	libSM.so.6 (it uses none of the library's symbols)
fixup for cf12bac:  don't link RT_LDFLAGS to rtapi_app
silence dpkg warning about useless libzmq dependency

    dpkg-shlibdeps: warning: package could avoid a useless dependency if
        [...]/rtapi_app_posix was not linked against libzmq.so.3
	(it uses none of the library's symbols)