Fix mc 100% CPU hang: select() non-epoll timeout and signal.h stdint include

relibc select_epoll() forced timeout=0 when any FD doesn't support epoll
(e.g. TTY on Redox), causing busy-loop. Poll with 100ms interval instead.

Also add stdint.h to signal/cbindgen.toml sys_includes so signalfd_siginfo
struct types (uint32_t, int32_t) resolve without build errors.

recipes/core/relibc/recipe.toml

@@ -17,6 +17,7 @@ patches = [
     "../../../local/patches/relibc/P3-netdb-lookup-retry-fix.patch",
     "../../../local/patches/relibc/P3-exec-root-bypass.patch",
     "../../../local/patches/relibc/P3-tcp-nodelay.patch",
+    "../../../local/patches/relibc/P3-select-not-epoll-timeout.patch",
 ]
 
 [build]