Fixes #1573.

We can't do the same for the Cabal lib because of the MIN_VERSION macros.

Can improve 'install -j' times a little bit for large install plans.

Old behaviour resulted in weird errors in some circumstances (e.g. if '~/.cabal'
was deleted between 'configure' and 'build').

Fixes #1570.

Cabal (the library) itself depends on these packages, so they should be
installed first. See #1486.

∙ At one point under OS X, ld required the mtime of the symbol table to be
  not older than that of the archive itself. This means that even copying an
  .a file required invoking ranlib to update the symbol table mtime.
∙ However running ranlib renders pointless the deterministic mode of #1537.
∙ As of at least 2008 according to the BUGS section of ranlib(1), this has
  no longer been necessary.

First introduction: 12b35902
Current implementation: af3da760

After invoking ar(1), replace each object file's metadata with zero for the
mtime, UID and GID, and 0644 for the file mode. Do not touch the existing
archive if the contents are the same.

This rewrites the previous patch to,
 ∙ also wipe UID, GID and file mode;
 ∙ do a single read/write for each header, and less seeking in general;
 ∙ do its work inside a temporary directory, via 'withTempDirectory';
   ∘ Which also deletes the temporary target when it's identical to the old.
 ∙ use Distribution.Compat.CopyFile.filesEqual;
 ∙ use the standard 'dieWithLocation' instead of invoking 'error'.

Niklas Hambüchen authored Aug 05, 2013 and Liyang HU committed Nov 05, 2013

We do this by not putting timestamps into the .a file,
and not touching it if is already there and the contents are the same.

Niklas Hambüchen authored Aug 05, 2013 and Liyang HU committed Nov 05, 2013

We need them to compare against, so that we can decide if we want to
write new files or keep the old ones untouched.

Initial support for parallel 'ghc --make'

Now the log contains the output of all install phases ('setup
configure/build/.../install') instead of only the last ('setup install' if the
build was succcesful).

We do this for 'install -j' already.

Installed packageids

Make the default case the first one, for readability. Tweak versions a little
bit.