Fixes #216: Size of SpscGrowableArrayQueue can exceeds max capacity

[franz1981]

Adjust producer limit in order to allow one more element to be added
in place of the unneeded JUMP when the max capacity producer buffer
has been allocated

[coveralls]

Pull Request Test Coverage Report for Build 446

• 2 of 2 (100.0%) changed or added relevant lines in 2 files are covered.
• 5 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.2%) to 69.204%

---

Files with Coverage Reduction	New Missed Lines	%
jctools-core/src/main/java/org/jctools/maps/NonBlockingHashMap.java	1	81.62%
jctools-core/src/main/java/org/jctools/queues/atomic/SpscGrowableAtomicArrayQueue.java	1	93.55%
jctools-core/src/main/java/org/jctools/maps/NonBlockingSetInt.java	3	77.65%

Totals
Change from base Build 443:	0.2%
Covered Lines:	5672
Relevant Lines:	8196

---

💛 - Coveralls

[franz1981]

@nitsanw I can add a test similar to the one provided by @yangyi438 if necessary, but I have already verified that it fixes the referenced issue :)
Sorry for the multiple changes of commit msg/PR name, but I was experimenting to reference the issue number into the commit msg to allow github to ref & close them in tandem :P

[nitsanw]

Please add the test.
Thanks for jumping in :-)

[franz1981]

@nitsanw No worries :)
I admit is not one of my most brilliant tests, but let me know if is enough 👍