RFR 8211360 : Change #if DEF to #if defined(DEF)

[Ivan Gerasimov]

Hello!

It's a followup for JDK-8211146.

With that fix several C-preprocessor statements of form #elif __linux__ 
were changed to more accurate #elif defined(__linux__).

grep found a few more occurrences of the same pattern, which also would 
better be cleaned up.

BUGURL: https://bugs.openjdk.java.net/browse/JDK-8211360
WEBREV: http://cr.openjdk.java.net/~igerasim/8211360/00/webrev/

Mach5 control build/testing went fine on all platforms.
Would you please help review?

-- 
With kind regards,
Ivan Gerasimov