build-sys: disable bz2 tarball and fix some am warnings

build-sys: disable bz2 tarball and fix some am warnings

Nobody needs the .bz2 tarball. We dont't even upload it to
kernel.org.

BTW we fix dozens of these automake warnings:

    automake-1.13/am/ltlibrary.am: warning: 'libblkid.la': linking libtool libraries using a non-POSIX
    automake-1.13/am/ltlibrary.am: archiver requires 'AM_PROG_AR' in 'configure.ac'

So we can remove -Wno-portability. The only warning left is this
last GNU-make'ism which somebody may fix when reading it:

   sys-utils/Makemodule.am:191: warning: addprefix sys-utils/,$(SETARCH_LINKS: non-POSIX variable name
   sys-utils/Makemodule.am:191: (probably a GNU make extension)
   Makefile.am:90:   'sys-utils/Makemodule.am' included from here

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>