Im trying to install fetchmail on my Slack 9.1 box and when I run configure I get this error and I can't figure out why:

root@phYre:~/fetchmail/fetchmail-6.2.5# ./configure
checking for a BSD-compatible install... /usr/bin/ginstall -c
checking whether build environment is sane... yes
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking build system type... i686-pc-linux-gnu
checking host system type... i686-pc-linux-gnu
checking for gcc... gcc
checking for C compiler default output... configure: error: C compiler cannot create executables
See `config.log' for more details.

And this is the relative output for config.log:
configure:1807: checking for gcc
configure:1823: found /usr/bin/gcc
configure:1833: result: gcc
configure:2077: checking for C compiler version
configure:2080: gcc --version </dev/null >&5
gcc (GCC) 3.2.3
Copyright (C) 2002 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

configure:2083: $? = 0
configure:2085: gcc -v </dev/null >&5
Reading specs from /usr/lib/gcc-lib/i486-slackware-linux/3.2.3/specs
Configured with: ../gcc-3.2.3/configure --prefix=/usr --enable-shared --enable-threads=posix --enable-__cxa_atexit --disable-checking --with-gnu-ld --verbose --target=i486-slackware-linux --host=i486-slackware-linux
Thread model: posix
gcc version 3.2.3
configure:2088: $? = 0
configure:2090: gcc -V </dev/null >&5
gcc: argument to `-V' is missing
configure:2093: $? = 1
configure:2117: checking for C compiler default output
configure:2120: gcc -O conftest.c >&5
/usr/lib/gcc-lib/i486-slackware-linux/3.2.3/../../../../i486-slackware-linux/bin/ld: cannot find /usr/lib/libc_nonshared.a
collect2: ld returned 1 exit status
configure:2123: $? = 1
configure: failed program was:
| #line 2096 "configure"

I think you probably need to install glibc.

OK i have glibc installed and now I get this error:
checking how to run the C preprocessor... /lib/cpp
configure: error: C preprocessor "/lib/cpp" fails sanity check
See `config.log' for more details

so I look in config.log and search for cpp and it returns this:
root@phYre:~/fetchmail-6.2.5# grep cpp config.log
configure:2889: gcc -E -traditional-cpp conftest.c
configure:2889: gcc -E -traditional-cpp conftest.c
configure:2889: /lib/cpp conftest.c
configure:2889: /lib/cpp conftest.c
configure:2971: result: /lib/cpp
configure:2996: /lib/cpp conftest.c
configure:2996: /lib/cpp conftest.c
configure:3070: error: C preprocessor "/lib/cpp" fails sanity check
ac_cv_prog_CPP=/lib/cpp
CPP='/lib/cpp'

How can I resolve this?

Try upgrading cpp.