GHC_PACKAGE_PATH in build.sh

[Yitzchak Gale]

To make sure it wasn't missed, I am pasting below the
following Haskell Platform build issue that was reported
on reddit:

http://www.reddit.com/r/haskell/comments/1f8730/basic_guide_on_how_to_install_ghcplatform_manually/

Just to clarify: I did not report this issue, and I don't know
anything more about it beyond what is below. If more
information is needed, perhaps replying on the reddit
thread would be helpful.

-Yitz

--- (snip) ---

A few of us in my department just tested this out and ran into an
issue. Just thought I'd post our solution in case it helps anyone
else.

For context, we are using departmental computers that do not allow the
use of sudo, so all installs must be local. Additionally, the Linux
distribution we use is a modified version of Slackware 13.37

If, when running make in the haskell-platform directory you run into
an error like this:

Setup: Use of GHC's environment variable GHC_PACKAGE_PATH is incompatible with
Cabal. Use the flag --package-db to specify a package database (it can be used
multiple times).

Error:
Configuring the HUnit-1.2.5.2 package failed
make: *** [build.stamp] Error 2

It could be because the build script is setting GHC_PACKAGE_PATH when
it doesn't need to. Our fix was to remove line 69 from the
scripts/build.sh file. This line looks like:
GHC_PACKAGE_PATH="${ORIG_GHC_PACKAGE_PATH}" \.

After removing that line, run make clean and then start the process
again (./configure ...).