Fix a few warnings
Fix warnings detected by gcc 14 when building with
SET(CMAKE_CXX_FLAGS "-Wall -Wextra -Wshadow -Woverloaded-virtual -Wno-deprecated -Wno-strict-overflow -Wno-array-bounds -Wunreachable-code -fdiagnostics-color=always -Wstringop-overflow -Wstringop-overread" CACHE STRING "")
SET(CMAKE_C_FLAGS "-Wall -Wextra -Wshadow" CACHE STRING "")
The fixes are mostly about shadowed variables and methods, unused var and invalid type comparisons
Edited by Mathieu Westphal (Kitware)