RFR 8017061: os_bsd.cpp contains code for UseSHM and UseHugeTLBFS

[Gerard Ziemski]

Hi all,

Please review this small fox that removes code from bsd platform, which implements unused (and untested) UseLargePages support.

Also, in this fix, I took opportunity to cleanup OS includes (there were unused and duplicated headers)

Bug: https://bugs.openjdk.java.net/browse/JDK-8017061
Webrev: http://cr.openjdk.java.net/~gziemski/8017061_rev1
Testing: passes Mach5 hs_tier1-7


Cheers