Add warning if compiling a configuration the runtime has not (yet) built.

This is useful when, for example, compiler and runtime was compiled with
CHPL_GMP=gmp (perhaps due to speculative build) but user has manually set
CHPL_GMP=none when calling chpl compiler.
Merge branch 'master' of github.com:chapel-lang/chapel into check-runtime-gen-path
Update runtime lib dir check based on review feedback.

* Fixes the if statement to use all make functions, instead of a combination of
  bash and make.
* Promotes the warning to an error.
* Updates the message to be more clear about the issue.
Add additional messaging when CHPL_DEVELOPER is set.

Also update FIXME comment.
more wordsmithing
Add test for the new warning message.
Wrap a long line.
Factor prediff script into separate script.
Add error different messaging for module.

The module is a binary install (a la RPM), so it does not make sense to tell
the user to rebuild. Instead, tell them to send the output of printchplenv to
the package maintainer.

The exact wording is probably not final here.
Remove fixme comment.
Add test with CHPL_DEVELOPER defined.
Merge pull request #573 from thomasvandoren/check-runtime-gen-path

Check runtime gen path.

Add a check when building generated C code to ensure the expected runtime
configuration has been compiled. If it has not, warn the user.

Reviewed by Greg and Brad