ALLJOYN-1510 fixed issue that SIGSEGV was seen on jre-1.6.0_34

When jre-1.6.0_34 was released the StackShadowPages size was increased
from 6 to 20.  Unfortantly this change caused our unit tests to SIGSEGV
To fix this issue when running the unit tests on a x86_64 build we will
manually specify the StackShadowPages to 6.

Change-Id: I4854a03314284721d644aa481f11515dae79a863
ALLJOYN-1510 Fixed x86 build failure related to StackShadowPages

Turns out setting <jvmargs value=""> will produce a runtime error.
When running on x86 StackShadowPages is set to 3 (the default value)
When running on x86_64 StackShadowPages is set to 6.  On newer JVMs
the default value is 20.  Having StackShadowPages set to 20 causes
unexpected SIGSEGV errors.

Change-Id: I11ee57fd2aa9f5f51ee3cc43b1630879ce4096c9