[openvsp] error: ‘CLOCK_MONOTONIC’ was not declared in this scope

[acxz]

[ 25%] Building CXX object exprparse/CMakeFiles/exprparse.dir/exprparse.cpp.o
/home/acxz/vcs/git/github/acxz/pkgbuilds/openvsp/src/buildlibs/DELABELLA-prefix/src/DELABELLA/delabella.cpp: In function ‘uint64_t uSec()’:
/home/acxz/vcs/git/github/acxz/pkgbuilds/openvsp/src/buildlibs/DELABELLA-prefix/src/DELABELLA/delabella.cpp:56:23: error: ‘CLOCK_MONOTONIC’ was not declared in this scope
   56 |         clock_gettime(CLOCK_MONOTONIC, &ts);
      |                       ^~~~~~~~~~~~~~~
/home/acxz/vcs/git/github/acxz/pkgbuilds/openvsp/src/buildlibs/DELABELLA-prefix/src/DELABELLA/delabella.cpp:56:9: error: ‘clock_gettime’ was not declared in this scope
   56 |         clock_gettime(CLOCK_MONOTONIC, &ts);
      |         ^~~~~~~~~~~~~

[acxz]

upstream issue: OpenVSP/OpenVSP#273