[Fix] Fix allocator mismatches with jemalloc

[Fix] Fix allocator mismatches with jemalloc

Resolve crashes caused by mixing system malloc and jemalloc allocators.
The issue occurred when getline() and hiredis used system malloc, but
rspamd's free() used jemalloc, causing segmentation faults on macOS and
potentially other platforms.

Changes:
- Add rspamd_getline() wrapper using g_malloc/g_realloc/g_free to avoid
  system malloc in getline()
- Replace getline() with rspamd_getline() in url.c, dns.c, lua_repl.c
- Fix memory leak in lua_repl.c by freeing input buffer on exit
- Configure hiredis allocators to use glib functions (jemalloc) in
  rspamd_init_libs()

This ensures all memory operations use the same allocator (jemalloc)
throughout rspamd, preventing allocator mismatch crashes.