Remove redundant includes of unistd.h (#5126)

src/nvim/os/fileio.c

@@ -4,7 +4,6 @@
 /// Neovim stuctures for buffer, with autocommands, etc: just fopen/fread/fwrite
 /// replacement.
 
-#include <unistd.h>
 #include <assert.h>
 #include <stddef.h>
 #include <stdbool.h>

src/nvim/os/fs.c

@@ -3,7 +3,6 @@
 #include <stddef.h>
 #include <assert.h>
 #include <limits.h>
-#include <unistd.h>
 #include <fcntl.h>
 #include <errno.h>
 

src/nvim/os/pty_process_unix.c

@@ -3,7 +3,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include <unistd.h>
 #include <termios.h>
 #include <sys/types.h>
 #include <sys/wait.h>