Use %zu printf format for type size_t

[edgar-bonet]

I am still using a 32-bit netbook, and even compiling stuff on it. Yes, I know it's outdated. While building goaccess, I got this GCC warning:

src/bin2c.c:119:39: warning: format ‘%lu’ expects argument of type ‘long unsigned int’,
but argument 4 has type ‘size_t’ {aka ‘unsigned int’} [-Wformat=]
  119 |   fprintf (f_output, "const char %s[%lu] = {", ident, file_size);
      |                                     ~~^               ~~~~~~~~~
      |                                       |               |
      |                                       |               size_t {aka unsigned int}
      |                                       long unsigned int
      |                                     %u

and the same warning on line 137.

This pull request fixes the printf format, which should be %zu.

[allinurl]

Awesome. Merged. Thank you!