>>> Source unpacked.
>>> Compiling source in /var/tmp/portage/sys-libs/db-4.5.20_p2/work/db-4.5.20/build_unix ...
 * QA Notice: USE Flag 'userland_GNU' not in IUSE for sys-libs/db-4.5.20_p2

!!! ERROR: sys-libs/db-4.5.20_p2 failed.
Call stack:
  ebuild.sh, line 1614:   Called dyn_compile
  ebuild.sh, line 971:   Called qa_call 'src_compile'
  environment, line 4818:   Called src_compile
  db-4.5.20_p2.ebuild, line 92:   Called econf '--prefix=/usr' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--datadir=/usr/share' '--sysconfdir=/etc' '--localstatedir=/var/lib' '--libdir=/usr/lib' '--enable-compat185' '--without-uniquename' '--enable-rpc' '--host=i686-pc-linux-gnu' '--enable-cxx' '--disable-tcl' '--disable-java' '--build=i686-pc-linux-gnu' '--disable-test' ''
  ebuild.sh, line 580:   Called die

!!! no configure script found
!!! If you need support, post the topmost build error, and the call stack if relevant.
!!! A complete build log is located at '/var/tmp/portage/sys-libs/db-4.5.20_p2/temp/build.log'.

!!! When you file a bug report, please include the following information:
GENTOO_VM=  CLASSPATH="" JAVA_HOME=""
JAVACFLAGS="" COMPILER=""
and of course, the output of emerge --info