Define a compatibility shim for errormonitor

[vchuravy]

Should fix #1375 on Julia 1.6

[codecov]

Codecov Report

Merging #1378 (b238cc5) into master (f7880a3) will increase coverage by 0.76%.
The diff coverage is 62.50%.

❗ Current head b238cc5 differs from pull request most recent head 572d3a9. Consider uploading reports for the commit 572d3a9 to get more accurate results

@@            Coverage Diff             @@
##           master    #1378      +/-   ##
==========================================
+ Coverage   78.02%   78.78%   +0.76%     
==========================================
  Files         121      119       -2     
  Lines        8954     8708     -246     
==========================================
- Hits         6986     6861     -125     
+ Misses       1968     1847     -121     

Impacted Files	Coverage Δ
lib/cudadrv/execution.jl	94.82% <ø> (ø)
lib/cudadrv/memory.jl	81.44% <ø> (ø)
lib/cudadrv/pool.jl	86.84% <0.00%> (ø)
src/pool.jl	74.78% <0.00%> (-1.94%)	⬇️
lib/cudadrv/stream.jl	93.58% <94.44%> (ø)
src/array.jl	86.07% <100.00%> (ø)
src/compiler/execution.jl	86.33% <100.00%> (ø)
lib/utils/memoization.jl	80.00% <0.00%> (-1.82%)	⬇️
lib/cudadrv/devices.jl	85.18% <0.00%> (-1.24%)	⬇️
src/compiler/reflection.jl	94.02% <0.00%> (-0.26%)	⬇️
... and 11 more

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[maleadt]

This should also exist on master. Rebased, and changed the version condition (@isdefined code is easily forgotten).