fix shared library builds (experimental)

[JuliusNmn]

this patch fixes undefined symbol errors when building with -DBUILD_SHARED_LIBS=on. building without the flag works too. only tested on macos.

[codecov[bot]]

Codecov Report

Merging #1226 (9fd02ec) into master (60ac82e) will not change coverage. Report is 9 commits behind head on master. The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1226   +/-   ##
=======================================
  Coverage   64.50%   64.50%           
=======================================
  Files         223      223           
  Lines       23667    23667           
=======================================
  Hits        15266    15266           
  Misses       8401     8401           

see 1 file with indirect coverage changes