Remove packages to allow migration

[Ilias Tsitsimpis <i.tsitsimpis@gmail.com>]

Hi team,

I plan to file RM reports for the following packages:

  * haskell-language-python[mipsel]
    Build killed with signal TERM after 150 minutes of inactivity

  * gitit[arm64]
    /usr/bin/ld.gold: internal error in fix_errata, at ../../gold/aarch64.cc:1960

  * haskell-stack[mips mipsel]
    Build depends on haskell-src-exts which is marked as Not-For-Us

None of the above packages have any reverse dependencies.
Should I go ahead with these RM reports?

Other than that, the remaining problems seems to be with agda and
haskell-lambdabot-haskell-plugins/lambdabot.

-- 
Ilias