Fix typos in public headers [ci skip]

Author: XrXr

include/ruby/internal/intern/select/win32.h

@@ -206,7 +206,7 @@ rb_fd_dup(rb_fdset_t *dst, const rb_fdset_t *src)
  * property  we heavily  touch  the  internals of  MSVCRT.   We `CreateFile`  a
  * `"NUL"` alongside of  a socket and directly manipulate  its `struct ioinfo`.
  * This is of  course a very dirty hack.   If we could design the  API today we
- * could use `CancellIoEx`.  But we are older than that Win32 API.
+ * could use `CancelIoEx`.  But we are older than that Win32 API.
  */
 static inline int
 rb_fd_select(int n, rb_fdset_t *rfds, rb_fdset_t *wfds, rb_fdset_t *efds, struct timeval *timeout)

include/ruby/internal/symbol.h

@@ -203,7 +203,7 @@ VALUE rb_id2str(ID id);
 
 /**
  * Obtain a frozen string representation of a symbol (not including the leading
- * colon). Done without any object allcoations.
+ * colon). Done without any object allocations.
  *
  * @param[in]  symbol  A ::rb_cSymbol instance to query.
  * @return     A frozen instance of ::rb_cString with the name of `symbol`.