cmake error while compiling

[mrtester2052]

Hello, I ran into this problem while trying to compile libopenshot-audio-0.1.6 under Ubuntu Studio 18.04 (bionic) on an Acer ES1-533 notebook, all dependencies were successfully installed, sorry for the eventual inconvenience, didn't know where to report this and/or ask for help (seems a cmake issue actually), some other people got the exact same error on different OSs and projects, the 2 "not found" lines near the end:

Terminal output after issuing "cmake ../" as instructed here
https://docs.google.com/document/d/1V6nq-IuS9zxqO1-OSt8iTS_cw_HMCpsUNofHLYtUNjM/pub

`--------------------------------------------------------------
---- Generating build files for openshot-audio (0.1.6)

-- Looking for XOpenDisplay in /usr/lib/x86_64-linux-gnu/libX11.so;/usr/lib/x86_64-linux-gnu/libXext.so
-- Looking for XOpenDisplay in /usr/lib/x86_64-linux-gnu/libX11.so;/usr/lib/x86_64-linux-gnu/libXext.so - found
-- Looking for gethostbyname
-- Looking for gethostbyname - found
-- Looking for connect
-- Looking for connect - found
-- Looking for remove
-- Looking for remove - found
-- Looking for shmat
-- Looking for shmat - found
-- Looking for IceConnectionNumber in ICE
-- Looking for IceConnectionNumber in ICE - found
-- Found X11: /usr/lib/x86_64-linux-gnu/libX11.so
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Looking for pthread_create
-- Looking for pthread_create - not found
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE
-- Found Doxygen: /usr/bin/doxygen (found version "1.8.13") found components: doxygen dot
-- Found DOXYFILE_IN: /home/papucho/Descargas/libopenshot-audio-0.1.6/Doxyfile.in
`
Any help would be greatly appreciated, thanks in advance.