RFR (S) 8224796: C code is not compiled correctly due to undefined "i386"

[Aleksey Shipilev]

Bug:
  https://bugs.openjdk.java.net/browse/JDK-8224796

x86_32 tier1 tests time out (actually, fail) because of this.

In short, recent change to compile C code with --std=c99 got "i386" undefined. Build system still
sets "i586", and we should really use that. I don't want to regress stuff much by globally replacing
i386->i586, so the new code handles *both* defines. This is what "handle both x86_64 and amd64"
block in LinuxDebuggerLocal.c already does.

I have not seen the failures on Mac due to ps_core.c, but it is better to be safe there as well.

Fix:
  http://cr.openjdk.java.net/~shade/8224796/webrev.01/

Testing: {x86_64, x86_32} tier1; jdk-submit (running)

-- 
Thanks,
-Aleksey