RFR: [9] 8043340 & 8043591: [macosx] Build system issues

[David DeHaven]

>>>> * Why remove MACOSX_VERSION_MIN=@MACOSX_VERSION_MIN@? I believe we still use this in some closed makefiles. Or is the idea that we instead will force the sdk name to 10.7? If so, then we need to still leave this in until every user (RE) has switched properly.
>>> I moved all that to closed, it's in the internal review for those changes. The value is now set in custom-spec.gmk instead of spec.gmk. It was not used anywhere in OpenJDK that I could find. When deploy/install get revamped we can just remove it entirely, that'll be easier if it's in closed.
>>> 
>>> It's referenced in make/bsd/makefiles/gcc.make, but that entire block is skipped if spec.gmk exists (confirmed by throwing garbage in there), and it defaults to 10.7.0 anyways.
>>> 
>> Actually, I thought on this some more (and read the closed review). I added that feature to be able to build on 10.8 and still have bits runnable on 10.7, and it's still used in the jdk through the CFLAGS_JDKLIB and friends. We cannot remove those until we can guarantee that all builds are done on macosx10.7 sdkroot (which I assume would also fix the issue). So at least for now, please leave those in the open. Also, by having these CFLAGS/LDFLAGS set, we are able to create compatible bits even if macosx10.7 isn't installed.
>> 
>> If we want to move towards using a specific sdkroot rather than the -mmacosx-version-min flags to control compatibility, then we should also add a default for macosx10.7 in configure. It would probably be good to add a default regardless.

Oops. Nevermind, I got overzealous in moving stuff around. I'll fix that.

-DrD-