moj ~ # emerge pkgconfig

 * IMPORTANT: 14 news items need reading for repository 'gentoo'.
 * Use eselect news to read news items.

Calculating dependencies... done!
[ebuild     U #] sys-libs/zlib-1.2.8-r1 [1.2.7]
[ebuild     U  ] virtual/libintl-0-r1 [0]
[ebuild     U  ] virtual/libiconv-0-r1 [0]
[ebuild  N     ] dev-lang/python-exec-2.0.1-r1  PYTHON_TARGETS="(jython2_5) (jython2_7) (pypy) (pypy3) (python2_7) (python3_2) (python3_3) (python3_4)"
[ebuild     U  ] dev-libs/libffi-3.0.13-r1 [3.0.11] USE="-pax_kernel%"
[ebuild  N     ] app-text/sgml-common-0.6.3-r5
[ebuild     U  ] virtual/libffi-3.0.13-r1 [3.0.11]
[ebuild  N     ] app-arch/unzip-6.0-r3  USE="bzip2 unicode -natspec"
[ebuild     U  ] dev-util/gtk-doc-am-1.20 [1.18]
[ebuild  N    ~] dev-libs/libgpg-error-1.15  USE="nls -common-lisp -static-libs"
[ebuild  N     ] dev-libs/libgcrypt-1.5.4-r1  USE="-static-libs"
[ebuild  NS    ] dev-lang/python-3.3.5-r1 [3.2.3] USE="gdbm ipv6 ncurses readline ssl threads xml -build -doc -examples -hardened -sqlite -tk -wininst"
[ebuild  NS    ] dev-lang/python-2.7.7 [3.2.3] USE="gdbm ipv6 ncurses readline ssl threads (wide-unicode) xml -berkdb -build -doc -examples -hardened -sqlite -tk -wininst"
[ebuild     U  ] dev-libs/libxml2-2.9.1-r4 [2.8.0-r3] USE="python*" PYTHON_TARGETS="python2_7%* python3_3%* (-python3_2) -python3_4%"
[ebuild  N     ] app-text/build-docbook-catalog-1.19.1
[ebuild  N     ] dev-libs/libxslt-1.1.28-r3  USE="crypt -debug -python -static-libs" PYTHON_TARGETS="python2_7"
[ebuild  N     ] app-text/docbook-xsl-stylesheets-1.78.0  USE="-ruby"
[ebuild  N     ] app-text/docbook-xml-dtd-4.1.2-r6
[ebuild     U  ] dev-libs/glib-2.40.0-r1 [2.32.4-r1] USE="(mime%*)" PYTHON_TARGETS="python2_7%*"
[ebuild     U  ] dev-util/pkgconfig-0.28-r1 [0.27.1]

The following mask changes are necessary to proceed:
#required by dev-libs/libxml2-2.9.1-r4, required by app-text/build-docbook-catalog-1.19.1, required by app-text/docbook-xsl-stylesheets-1.78.0, required by app-text/docbook-xml-dtd-4.1.2-r6, required by dev-libs/glib-2.40.0-r1, required by dev-util/pkgconfig-0.28-r1[-internal-glib], required by pkgconfig (argument)
# /etc/portage/package.mask:
=sys-libs/zlib-1.2.8-r1

NOTE: The --autounmask-keep-masks option will prevent emerge
      from creating package.unmask or ** keyword changes.

Use --autounmask-write to write changes to config files (honoring CONFIG_PROTECT).