Fix std::exeception catch-by-reference gcc9 compile error

[davidwendt]

Compile error (for gcc-9) created by change in #7254 as mentioned in the following comment.
#7254 (comment)

Core C++ Guidelines for catching exceptions says to always catch by reference.
Polymorphism is supported only with pointers and references.
http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Re-exception-ref

[codecov]

Codecov Report

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@@              Coverage Diff               @@
##             branch-0.19    #7380   +/-   ##
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  Coverage               ?   82.21%           
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  Files                  ?      100           
  Lines                  ?    16971           
  Branches               ?        0           
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  Hits                   ?    13953           
  Misses                 ?     3018           
  Partials               ?        0           

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[davidwendt]

@gpucibot merge