Fix type mismatch

[michaelortmann]

Found by: michaelortmann Patch by: michaelortmann Fixes:

One-line summary:

Additional description (if needed): Fixes the following compiler warning:

modules.c:98:13: warning: type of 'argv0' does not match original declaration [-Wlto-type-mismatch]
   98 | extern char argv0;
      |             ^
./main.c:86:7: note: 'argv0' was previously declared here
   86 | char *argv0;
      |       ^

Test cases demonstrating functionality (if applicable):