Compiling Perl Module fail

[dominix]

I am using Perl-5.8.1 from F liu.
modules install work fine with pure perl modules
but I got the same error for every .c file I try
to compile with cpan.
Error! E1100: Definition of macro '__attribute__' \
not identical to previous definition

for example:
/usr/include/sys/cdefs.h(111): Error! E1100: Definition of macro
'__attribute__' not identical to previous definition

does someone know what is this __attribute__ about ?

thks
--
Dominix