Revert "add OPENSSL_X509_CERT_FILE to the `git` command environment"

This reverts commit 88b5578a579ca7eefc8ac5507f9a5be3cc3684ca because of the
following issues:

 1) If $OPENSSL_X509_CERT_FILE is set in the current shell environment, then
    its value will overwrite any settings the user may have configured in
    http.sslCAInfo via git-config(1). If you are unaware of the wrapper, then
    this behavior is totally unexpected as $OPENSSL_X509_CERT_FILE is not
    supposed to have an effect on Git.

 2) The patch makes it impossible for Git users to use the $GIT_SSL_CAINFO
    environment variable as documented in git-config(1), because anything set
    there will be overwritten with the value of $OPENSSL_X509_CERT_FILE (which
    might be empty).

 3) The patch breaks other builds of packages that depend on Git, i.e.
    <http://hydra.nixos.org/build/11995872/nixlog/1/raw>.
Merge pull request #3024 from third3ye/patch-4

The folder $url/steam/archive seems to be empty...
gsl: update to version 1.16
cppcheck: update from 1.64 to 1.65
haskell-network-transport-tcp: fix build with ghc < 7.8.2
Added distributed-process 0.5.
Bump binary version dependency of rank1dynamic, distributed-static, network-transport-* to 0.7.2.1.
retroshare: place plugins at proper place

Now they can be used.
Moved package overrides from haskell-packages.nix to haskell-defaults.nix.
Removed binary argument from networkTransport and networkTransportTcp
Add binary to networkTransport again.
Merge pull request #2983 from jwiegley/zlib

Do not use static-libgcc flag on Darwin
Merge pull request #2986 from jwiegley/ncurses

ncurses: apply a patch on Darwin for a clang bug
git-annex: Build on Darwin, let Cabal determine proper flags
Merge pull request #3031 from jwiegley/proofgeneral

proofgeneral_4_3_pre: Add expression needed for current prooftree
Merge remote-tracking branch 'upstream/master'
tig: enable command line history/completion support

Since version 2.0, tig can use readline for history/completion support,
so add readline as a build input.

Increases closure size from 53 MiB to 54 MiB.
Add hackage mirror to mirrors.nix
gccApple: Patches for building on Mavericks
php-5.4: Do not build with mssql support on Darwin
Fix broken checksums and update to version 4.2.018.