/usr/lib is already part of the paths in which find_library will search in). However, setting it in PATHS will find the library with maximum priority there even if the library is also available in some other location (for example, when qwt is available in an activated conda environment).
/usr/libis already part of the paths in whichfind_librarywill search in). However, setting it inPATHSwill find the library with maximum priority there even if the library is also available in some other location (for example, when qwt is available in an activated conda environment).