RFR: 8231953: Wrong assumption in assertion in oop::register_oop

[christoph.goettschkes at microdoc.com]

Hi,

please review the following changeset. This patch makes the 
CheckUnhandledOops feature work on 32-bit ARM platforms. On this platform, 
the os::current_frame() function does not return a valid frame in thumb 
mode [1]. I removed the failing assertion, since it does not hold on all 
supported platforms. I didn't want to introduce architecture specific code 
into that feature, just for an assertion.

This fixes the hotspot tier1 test 
"runtime/CheckUnhandledOops/TestOutOfMemory.java" mentioned in the issue.

Bug: https://bugs.openjdk.java.net/browse/JDK-8231953
Webrev: https://cr.openjdk.java.net/~bulasevich/8231953/webrev.00/

Thanks,
Christoph

[1] 
https://hg.openjdk.java.net/jdk/jdk/file/30a9612a657d/src/hotspot/os_cpu/linux_arm/os_linux_arm.cpp#l224