tcp.h: present but cannot be compiled

[step]

Linux 2.6.1-gentoo #1 SMP Wed Jan 28 21:11:56 EET 2004 i686 Intel(R)
Pentium(R) 4 CPU 2.40GHz GenuineIntel GNU/Linux


>>> emerge (5 of 20) kde-base/kdenetwork-3.2.0 to /
>>> md5 src_uri ;-) kdenetwork-3.2.0.tar.bz2
>>> Unpacking source...
>>> Unpacking kdenetwork-3.2.0.tar.bz2 to
/var/tmp/portage/kdenetwork-3.2.0/work
RUNNING FROM extra_functions.sh
 * Applying
linuxwirelesswidget.cpp.diff...                                               [ 
ok ]
>>> Source unpacked.
configure: WARNING: If you wanted to set the --build type, don't use
--host.
    If a cross compiler is detected then

.....


checking for jasper... no
checking linux/tcp.h usability... no
checking linux/tcp.h presence... yes
configure: WARNING: linux/tcp.h: present but cannot be compiled
configure: WARNING: linux/tcp.h: check for missing prerequisite headers?
configure: WARNING: linux/tcp.h: proceeding with the preprocessor's
result
configure: WARNING:     ## ------------------------------------ ##
configure: WARNING:     ## Report this to address@hidden ##
configure: WARNING:     ## ------------------------------------ ##
checking for linux/tcp.h... yes
checking linux/if_ppp.h usability... no
checking linux/if_ppp.h presence... yes
configure: WARNING: linux/if_ppp.h: present but cannot be compiled
configure: WARNING: linux/if_ppp.h: check for missing prerequisite
headers?
configure: WARNING: linux/if_ppp.h: proceeding with the preprocessor's
result
configure: WARNING:     ## ------------------------------------ ##
configure: WARNING:     ## Report this to address@hidden ##
configure: WARNING:     ## ------------------------------------ ##
checking for linux/if_ppp.h... yes
checking net/errno.h usability... no
checking net/errno.h presence... no
checking for net/errno.h... no
checking net/if_ppp.h usability... yes
checking net/if_ppp.h presence... yes
checking for net/if_ppp.h... yes
checking asm/param.h usability... yes