Don't have make limit the number of jobs based on load average on OS X.
Don't have make limit the number of jobs based on load average on OS X.

This makes build-cocoa around 25% faster on my MacBook Pro, decreasing
the time taken from ~23 minutes down to ~17 minutes.

The way that OS X computes load average is somewhat different than
Linux. Building with a limit of only 4 jobs can easily send the load
average up around 20. This results in substantially less parallelism
than expected. Rather than trying to determine a reasonable load average
for make to limit itself to on OS X, I've opted to just disable limiting based
on load average.

realm/realm-core,realm/realm-core,realm/realm-core,realm/realm-core,realm/realm-core,realm/realm-core,realm/realm-core