vim: move long_u from vim.h to types.h

Seems to make no difference to the main binary, but it helps the tests a bit
further along.

src/nvim/memfile_defs.h

@@ -1,6 +1,8 @@
 #ifndef NVIM_MEMFILE_DEFS_H
 #define NVIM_MEMFILE_DEFS_H
 
+#include "nvim/types.h"
+
 typedef struct block_hdr bhdr_T;
 typedef long blocknr_T;
 

src/nvim/types.h

@@ -10,6 +10,11 @@
 
 #include <stdint.h>
 
+// Make sure long_u is big enough to hold a pointer.
+// On Win64, longs are 32 bits and pointers are 64 bits.
+// For printf() and scanf(), we need to take care of long_u specifically.
+typedef unsigned long long_u;
+
 /*
  * Shorthand for unsigned variables. Many systems, but not all, have u_char
  * already defined, so we use char_u to avoid trouble.

src/nvim/vim.h

@@ -58,11 +58,6 @@ Error: configure did not run properly.Check auto/config.log.
 
 #define NUMBUFLEN 30        /* length of a buffer to store a number in ASCII */
 
-// Make sure long_u is big enough to hold a pointer.
-// On Win64, longs are 32 bits and pointers are 64 bits.
-// For printf() and scanf(), we need to take care of long_u specifically.
-typedef unsigned long long_u;
-
 # define MAX_TYPENR 65535
 
 /*