Fix gcc warnings #895

Job	Run time
Build for 32-bit	34s
macOS	1m 18s
RDMA support enabled	23s
CMake 3.7.0 (min. required)	34s
Build with make	5m 7s
Installation tests	43s
Run static checkers	29s
Windows (Cygwin)	2m 18s
Build with CMake and thread-sanitizer [clang-20, cmake-4.0, RelWithDebInfo]	3m 30s
Windows	1m 33s
Build with CMake and thread-sanitizer [gcc-14, cmake-4.0, RelWithDebInfo]	3m 24s
Build with CMake and leak-sanitizer [gcc-14, cmake-4.0, RelWithDebInfo]	3m 13s
Build with CMake [gcc-14, cmake-4.0, Release]	3m 1s
Build with CMake and address-sanitizer [clang-20, cmake-4.0, RelWithDebInfo]	3m 36s
Build with CMake and undefined-sanitizer [clang-20, cmake-4.0, RelWithDebInfo]	3m 29s
Build with CMake [clang-14, cmake-3.13, Release]	4m 27s
Build with CMake and undefined-sanitizer [gcc-14, cmake-4.0, RelWithDebInfo]	3m 17s
Build with CMake and leak-sanitizer [clang-20, cmake-4.0, RelWithDebInfo]	3m 43s
Build with CMake and address-sanitizer [gcc-14, cmake-4.0, RelWithDebInfo]	3m 31s
Windows (MinGW64)	1m 17s
Build with CMake [clang-20, cmake-4.0, Release]	3m 16s
Build with CMake [gcc-9, cmake-3.13, Release]	3m 10s
	55m 53s

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