Add ARMv7 longjmp bugfix

[awehrfritz]

Motivation and Context

Backport bugfix for ARMv7 to zfs 0.8.5, as suggested in #10722 (comment)

Description

The kernel module in the zfs 0.8-branch has been broken on the 32-bit ARMv7 platform (armhf). The issue has been reported in #9957 and fixed in #9967 (ab16c87). This PR backports the fix to the 0.8 release branch.

How Has This Been Tested?

Tested within the original PR (#9967). Furthermore, I included the patch in a local Debian package build where I apply this patch to the 0.8.4 release and use it ever since on my production system (a Helios4 based on the ARMv7 architecture).

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the ZFS on Linux code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (zfs-0.8.5-staging@6b18d7d). Click here to learn what that means.
The diff coverage is n/a.

@@                 Coverage Diff                  @@
##             zfs-0.8.5-staging   #10731   +/-   ##
====================================================
  Coverage                     ?   78.67%           
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  Files                        ?      381           
  Lines                        ?   118574           
  Branches                     ?        0           
====================================================
  Hits                         ?    93283           
  Misses                       ?    25291           
  Partials                     ?        0           

Flag	Coverage Δ
#kernel	79.07% <0.00%> (?)
#user	67.18% <0.00%> (?)

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