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.
Fix Coverity issue 1212346

Coverity was (I believe) correctly complaining about a possible null
dereference during generic resolution.  I looked through the filterCandidates
call heirarchy and it struck me as possible (though very unlikely) for a
control flow to reach that point when best was non-null but best->fn was.  To
fix, I added a check to best->fn to ensure it was non-null before the access
was performed.
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.
Add a comment to the change.

Tom pointed out that this extra check probably means we should restructure
resolveNormalCall.  This isn't a high priority for me, but it seems good to
note, so I added a note.
Merge branch 'master' into coverity1212346
Skip new pidigits tests if gmp == none.
Merge pull request #572 from lydia-duncan/coverity1212346

Fix Coverity issue 1212346 [reviewed by hilde]

Coverity was (I believe) correctly complaining about a possible null
dereference during generic resolution. I looked through the filterCandidates
call heirarchy and it struck me as possible (though very unlikely) for
control flow to reach that point when best was non-null but best->fn was. To
fix, I added a check to best->fn to ensure it was non-null before the access
was performed.
Merge pull request #574 from thomasvandoren/skip-new-pidigits-if-no-gmp

Skip new pidigits tests if gmp == none.
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.
Added 21-capture-in-cobegin.compopts
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
Merge pull request #575 from vasslitvinov/add-savec-to--21-capture-in-cobegin

Added 21-capture-in-cobegin.compopts

This test has been failing occasionally in nightly testing, and I haven't been able to reproduce it.
Have it saved the generated C code so I can examine it when it does fail.