tests/ssl: fix memcpy signature for 32-bit systems

[StefanKarpinski]

No description provided.

[codecov-commenter]

Codecov Report

Merging #89 into master will increase coverage by 2.70%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #89      +/-   ##
==========================================
+ Coverage    7.51%   10.21%   +2.70%     
==========================================
  Files           2        2              
  Lines         133      137       +4     
==========================================
+ Hits           10       14       +4     
  Misses        123      123              

Impacted Files	Coverage Δ
src/lC_curl_h.jl	6.45% <0.00%> (+2.31%)	⬆️
src/LibCURL.jl	46.15% <0.00%> (+4.48%)	⬆️

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[StefanKarpinski]

I'm going to merge this since it passes CI and it's an uncontroversial bugfix: the signature for memcpy is simply wrong on any 32-bit platform (and segfaults there).