-/* Wrapper for the body of signal handlers. Call this function from
- any SIGINT handler which needs to access GDB data structures or
- escape via longjmp. If IMMEDIATE_P is set, this triggers either
- immediately (for POSIX platforms), or from gdb_select (for
- MinGW). If IMMEDIATE_P is clear, the handler will run the next
- time we return to the event loop and any current select calls
- will be interrupted. */