RFR: 8305481: gtest is_first_C_frame failing on ARM

[Vladimir Petko]

os::current_frame() is stubbed out on the Linux Arm Thumb platform [1]
This causes gtest 'is_first_C_frame' to fail. 


[ RUN      ] os.is_first_C_frame_vm
./test/hotspot/gtest/runtime/test_os.cpp:890: Failure
Value of: os::is_first_C_frame(&cur_frame)
  Actual: true
Expected: false
[  FAILED  ] os.is_first_C_frame_vm (0 ms)

This pull request disables the test for ARM Thumb.

[1] https://github.com/openjdk/jdk/blob/0deb648985b018653ccdaf193dc13b3cf21c088a/src/hotspot/os_cpu/linux_arm/os_linux_arm.cpp#L219

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Commit messages:
 - disable is_first_C_frame on ARM Thumb

Changes: https://git.openjdk.org/jdk/pull/13292/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13292&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305481
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13292.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13292/head:pull/13292

PR: https://git.openjdk.org/jdk/pull/13292