Updating countMemory test for darwin and cleaning up a bit in general

This commit makes our countMemory test work on darwin by extending the
.prediff script to query the amount of physical memory using the Mac's
'system_profiler' script.  It also makes a small adjustment in the
.makegood file to print trailing ".0"s on round numbers in order to
match Chapel's default format for printing reals.

While here, I removed all the hardcoded machine-specific files that we
have, as none of them are still actively being used.  This also
permitted me to make the .gitignore rule for this directory much
simpler, using a wildcard character.
Oops, fixed my previous implementation

My previous implementation of getting a trailing .0 worked for
integer values stored as floating point, but not for floating
point numbers that would, by default, print multiple decimal
places.  Duh.  This fixes that by doing string post-processing.
However, I'm now getting different rounding modes in C vs. Perl
for reasons I can't fathom yet.
Fix previous rounding error

It turns out that the issue was that I wasn't first computing a
floating point number before sprintf-ing it.  I have no idea
why the direct sprintf-of-an expression would behave differently
than storing it in a variable first, but it seems to.
Responding to Elliot's suggestions

* changed from uname -s to chpl_platform.py on the argument that
  any futzing with uname will already have taken place there (i.e.,
  why duplicate that logic if corner cases come up in the future).
  One slight weirdness here is that I choose --target (since that's
  where the code is running) even though the .prediff script itself
  is running on the host (i.e., we're basically assuming that host
  will equal target for this test, but that's already true of the
  test).

* changed from the old way I was querying physical memory to
  'sysctl hw.memsize'.  For whatever reason, this was the second
  suggestion on the page that google took me to, so once the
  first suggestion worked, I never bothered looking at the second.
  Fixed up the math based on this change.

* removed some debugging comments (left in on purpose to aid future
  debugging, but I'm not opposed to removing them either).
Fix two prediffs to work on all OSes

The stock sed on darwin is not GNU or even a modern BSD version and you
can not write an extend regex command that works in both. I've changed
the scripts to be python which will work the same on all the platforms
we support.
More response to Elliot's comments

* switched to sysctl -n in order to avoid having to parse out an integer
* renamed pre-existing 'memfree' variable to 'memFreeInKB' to make its
  implied units clearer.
D'oh!  A debug printf got away from me.  Removing it.
Merge pull request #691 from bradcray/fix-countmemory-for-mac

Fix memory counting tests for mac

[reviewed by @ronawho ]

This commit makes our memory counting tests portable to Mac
without user involvement, and also cleans things up a bit.

As background, the test is used to determine whether the
Chapel query for the amount of physical memory a locale
owns is working correctly by comparing it to the results
of /proc/meminfo by default. Macs don't support
/proc/meminfo by default, so in the past, we've manually
created .good files for our Macs and used those instead.
But this is a hassle. The lack of such a .good file on
our new Mac testing platform, for example, has caused
this test to fail (as it would on individual developers'
Macs now that more people are using them).

Doing a quick google search, I found a Mac-happy way to
get the amount of physical memory from the command-line
and substituted that in, in the event that chpl_platform.py is
darwin (in countMemory.prediff).

From there, one other change was required: When the
amount of physical memory is an integer, it seems that
we got a bad match because the Perl scripts would
printf the value '8' where Chapel would print '8.0'.
For this reason, I had to do some processing in the
.makegood script to add a trailing '.0' to such cases.
This was complicated only by my own poor knowledge of
Perl (including not anticipating that computing a
floating point expression, assigning it to a value, and
then converting it to a string would give a different
result than simply converting the expression to a
string (?!)

While here, I noted that most of the hard-coded machine
.good files that we have are Macs (and ones that we
don't run on anymore), so removed them, as well as a
few other machines that are long-since retired. So
I ended up removing all the ..good files and
simplified the .gitignore file as a result.
Merge pull request #694 from Kyle-B/kb-fix-non-portable-prediffs

Fix two prediffs to work on all OSes

The stock sed on darwin is not GNU or even a modern BSD version and you
can not write an extend regex command that works in both. I've changed
the scripts to be python which will work the same on all the platforms
we support.