psql front-end tool, unsetenv failed in solaris

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                        POSTGRESQL BUG REPORT TEMPLATE
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Your name        :    Ki-hyun Yoon
Your email address    :       abird@seedvr.com


System Configuration
---------------------
  Architecture (example: Intel Pentium)      : Intel Pentium

  Operating System (example: Linux 2.0.26 ELF)     : Solaris x86 2.7

  PostgreSQL version (example: PostgreSQL-6.4.2)  :   PostgreSQL-6.4.2

  Compiler used (example:  gcc 2.8.0)        : gcc 2.8.1


Please enter a FULL description of your problem:
------------------------------------------------
There is no unsetenv function in solaris environment.
So, I failed in compiling psql front-end tool.
Umm, I first compiled postgresql with no with-mb option.
Next I reconfigured it with with-mb option.
This only can exist in MULTI-BYTE environment.

I changed that line.
!   unsetenv("PGCLIENT...");
!   putenv("PGCLIENT...=");

This is very simple port-problem.
Thanks.