Evaluate the compiler warnings

Now the build logs contains some warnings, see for example: 

http://10.212.0.130/coin/logview/tqtc-boot2qt/qtsaferenderer/6e4674e37e46d0d43725f275bc18df0e309c1ef9/LinuxRHEL_7_6x86_64INTEGRITYINTEGRITY_11_04armv7GCCqtci-linux-RHEL-7.6-x86_64-c2b914DisableTests/898617e51db79f915c86d2726f7e713d84c37008/build_1612778133

and search "warning " (including the whitespace) to see the corresponding lines.

Check if the threat warnings as errors could bring any value.

And also check if these can be spotted by the Qt Creator language model, and is there a need to tweak the corresponding editor settings.