Fix size_t format specifiers on 32 bit systems

[tatokis]

This fixes the following warnings on 32 bit systems

[60/108] Compiling C object i3.p/src_regex.c.o
In file included from ../include/all.h:40,
                 from ../src/regex.c:10:
../src/regex.c: In function ‘regex_new’:
../include/log.h:29:33: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 2 has type ‘size_t’ {aka ‘unsigned int’} [-Wformat=]
   29 | #define ELOG(fmt, ...) errorlog("ERROR: " fmt, ##__VA_ARGS__)
      |                                 ^~~~~~~~~
../src/regex.c:35:9: note: in expansion of macro ‘ELOG’
   35 |         ELOG("PCRE regular expression compilation failed at %lu: %s\n",
      |         ^~~~
[93/108] Compiling C object i3-input.p/i3-input_main.c.o
../i3-input/main.c: In function ‘finish_input’:
../i3-input/main.c:173:29: warning: format ‘%ld’ expects argument of type ‘long int’, but argument 2 has type ‘size_t’ {aka ‘unsigned int’} [-Wformat=]
  173 |     printf("occurrences = %ld\n", cnt);
      |                           ~~^     ~~~
      |                             |     |
      |                             |     size_t {aka unsigned int}
      |                             long int
      |                           %d 

[orestisfl]

Ευχαριστούμε ;)