sparse: Fix mingw_main() argument number/type errors

Sparse issues 68 errors (two errors for each main() function) such
as the following:

      SP git.c
  git.c:510:5: error: too many arguments for function mingw_main
  git.c:510:5: error: symbol 'mingw_main' redeclared with different type \
    (originally declared at git.c:510) - different argument counts

The errors are caused by the 'main' macro used by the MinGW build
to provide a replacement main() function. The original main function
is effectively renamed to 'mingw_main' and is called from the new
main function. The replacement main is used to execute certain actions
common to all git programs on MinGW (e.g. ensure the standard I/O
streams are in binary mode).

In order to suppress the errors, we change the macro to include the
parameters in the declaration of the mingw_main function.

Unfortunately, this change provokes both sparse and gcc to complain
about 9 calls to mingw_main(), such as the following:

      CC git.o
  git.c: In function 'main':
  git.c:510: warning: passing argument 2 of 'mingw_main' from \
    incompatible pointer type
  git.c:510: note: expected 'const char **' but argument is of \
    type 'char **'

In order to suppress these warnings, since both of the main
functions need to be declared with the same prototype, we
change the declaration of the 9 main functions, thus:

    int main(int argc, char **argv)

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git.c

@@ -507,8 +507,9 @@ static int run_argv(int *argcp, const char ***argv)
 }
 
 
-int main(int argc, const char **argv)
+int main(int argc, char **av)
 {
+	const char **argv = (const char **) av;
 	const char *cmd;
 
 	startup_info = &git_startup_info;