regression test failed on 6.5

Hi,

I'm a newbie and have some questions:

A regression test agaist a new installed 6.5 failed on
items int2, int4 and geometry.  It was in Linux 2.0.35.
The posgresql was compiled by:

  $ gcc -v
  Reading specs from /usr/lib/gcc-lib/i386-pc-linux-gnulibc1/egcs-2.91.66/specs
  gcc version egcs-2.91.66 19990314 (egcs-1.1.2 release)

I tried the 6.4.2 before in the same enviroment with the
same compiler.  The regression test went 100% ok.  However,
I was not able to create a field by int8[] type:

  postgres=> create table test (v int8[]);
  ERROR:  Unable to locate type name '_int8' in catalog

But

  postgres=> create table test(v int8);
  CREATE
  postgres=> drop table test;
  DROP
  postgres=> create table test(v int4[]);
  CREATE

I thought int8 is one of the basic type like int4. Anything
I did wrong? (PS: same error message in 6.5)

Regards,

Min