patch 9.1.1662: Issues with proto files: missing or inconsistent prototypes.

Problem:  Issues with proto files: missing or inconsistent prototypes.
Solution: Update ifdefs, move typedefs, fix prototype declaration
          (Hirohito Higashi)

This change focuses on fixes and tweaks found while working on #18045 for
the proto/*.pro files.

The following fixes and tweaks have been made:

- Fixed a prototype declaration where the variable name differed from
  the function definition.
- Removed a prototype declaration without a function body.
- Fixed a problem where a prototype declaration was not created for a
  function definition enclosed in a #if directive because it lacked ||
  defined(PROTO).
- Moved typedef struct soundcb_S soundcb_T; from proto/sound.pro to
  vim.h.
- Other small tweaks.

The make proto mechanism remains unchanged.

closes: #18058

Signed-off-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/term.c

@@ -2449,7 +2449,7 @@ vim_tgetstr(char *s, char_u **pp)
 }
 #endif // HAVE_TGETENT
 
-#if defined(HAVE_TGETENT) && (defined(UNIX) || defined(VMS) || defined(MACOS_X))
+#if defined(HAVE_TGETENT) && (defined(UNIX) || defined(VMS) || defined(MACOS_X)) || defined(PROTO)
 /*
  * Get Columns and Rows from the termcap. Used after a window signal if the
  * ioctl() fails. It doesn't make sense to call tgetent each time if the "co"