[8u20] post-commit review and heads-up: RT-35955: Mac: Intermittent build failures in task graphics:ccMacFontT2K

[Kevin Rushforth]

I just pushed a fix for the following bug:

https://javafx-jira.kenai.com/browse/RT-35955

The fix, which is really just a workaround for an unknown gcc issue on 
Mac, is to disable parallel native compilation on Mac by default. The 
"NUM_COMPILE_THREADS" property controls the number of concurrent 
compilation threads that run. On Mac this property is now set to 1 by 
default.

Developers can set "NUM_COMPILE_THREADS=8", for example, in their 
gradle.properties file or pass "-PNUM_COMPILE_THREADS=8" on the command 
line to enable 8 threads to run in parallel and speed up the build.

I filed https://javafx-jira.kenai.com/browse/RT-36433 as a follow-on 
issue to investigate the root cause and re-enable the parallelism. Since 
we've switch to native font rasterization on Mac (using coretext), we 
might end up removing the T2K code from our build at some point anyway 
at which point the issue will be moot (if in fact it really doesn't ever 
happen on any other module)

-- Kevin