Improve strlen

[eeropomell]

[mosolovsa]

Please consider to:

1. Fix the line while (s[++x); (missing enclosing square bracket):
2. Think about edge cases, e.g. providing empty string as an argument. Preincrement will set x to 1 skipping the character at index 0, introducing a bug. Test:

#include <stdio.h>
#include <string.h>

typedef size_t uint;

uint
broken_strlen(const char *s)
{
  int x = 0;
  while (s[++x]);

  return x;
}

int main() {
    const char *shit_happens = "\0some mem after the c str";

    uint len_empty = strlen(shit_happens);
    uint broken_len_empty = broken_strlen(shit_happens);

    printf("len_empty = %zu, broken_len_empty = %zu!\n", len_empty, broken_len_empty);
    return 0;
}

3. Remove .vscode directory from PR