Error while upgrading FreeBSD-Release6.1 to CURRENT

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Dear all:

I have a problem while upgrading FreeBSD-6.1 to CURRENT. First of all, I 
encountered config version mismatch. So I re-buildworld, and that error 
disappeared. However, gcc version for FreeBSD-6.1 seems old since 
CURRENT needs version 4.x. So I went to ports tree and install latest 
gcc4.2. But after buildkernel, there was still error message: cc1: 
error: unrecognized command line option "-mno-align-long-strings"
                                    cc1: error: unrecognized command 
line option "-fformat-extensions"

I don't know what else I could do. Please help me out.

Thanks.

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