RFR: JDK-8072101 Support linux_x86 build

[Sergey Nazarkin]

issue: https://bugs.openjdk.java.net/browse/JDK-8072101
review: http://cr.openjdk.java.net/~snazarki/8072101/

The fix just allow to put platform binaries into correct named folder. 
No code/script is necessary but x64 host must provide additional key 
(-m32) at TARGET_C_FLAGS/TARGET_CXX_FLAGS/TARGET_LD_FLAGS to generate 
correct code.
ARM is left as default build target.

-- 
/Sergey