LibJS/JIT: Add missing unistd.h include (fixes Clang build)

Author: https://github.com/awesomekling
Commit: a7bad26b63
Pull-request: https://github.com/SerenityOS/serenity/pull/21619
Reviewed-by: https://github.com/Hendiadyoin1

Userland/Libraries/LibJS/JIT/Compiler.cpp

@@ -9,6 +9,7 @@
 #include <LibJS/JIT/Compiler.h>
 #include <LibJS/Runtime/ValueInlines.h>
 #include <sys/mman.h>
+#include <unistd.h>
 
 namespace JS::JIT {