Due to use of strcasecmp() or similar C API.
Maybe HAVE_STRINGS_H is needed ? If so which platforms needs this ?
clang18 default warning cleanup (strict)
This commit makes the code (mostly) C99-compatible, enabling to compile
it without the -Wno-error=implicit-function-declaration flag. This
way, Magic becomes usable on arm64 architectures, specifically on Apple
computers with M1/M2 SoC.