enabling ffnvcodec causes build problems in Ubuntu

[borovik135]

Setting fletch_ENABLE_ffnvcodec=ON causes build issues in Ubuntu, i.e. $ make [ 2%] Performing install step for 'ffnvcodec' install: cannot change permissions of ‘/usr/local/include/ffnvcodec’: No such file or directory make[3]: [Makefile:14: install] Error 1 make[2]: [CMakeFiles/ffnvcodec.dir/build.make:74: build/src/ffnvcodec-stamp/ffnvcodec-install] Error 2 make[1]: [CMakeFiles/Makefile2:138: CMakeFiles/ffnvcodec.dir/all] Error 2 make: [Makefile:130: all] Error 2

Machine details (please complete the following information):

• OS: Ubuntu 20.04 LTS
• CMake version 3.16.3
• Compiler c++ (Ubuntu 8.4.0-3ubuntu2) 8.4.0
• Fletch master bb14e83

[daniel-riehm]

Fixed in #719