Version-Release number of selected component (if applicable):
mc-4.5.55-12

Whatever the mc-4.5.55-mb.patch is supposed to do, it doesn't:
+                      if((*text & 0xC0) == 0xC0) { /* start of multi byte char
+                              if((*text & 0xC0) != 0x80)
+                                      len = 2;
+                              else if((*text & 0xC0) != 0x800)
+                                      len = 3;
+                              else if((*text & 0xC0) != 0x10000)
+                                      len = 4;
+                              SLsmg_write_nstring(text, len);
+                              text = text + len;
+                      }

The above is equivalent to
+                      if((*text & 0xC0) == 0xC0) { /* start of multi byte char
+                              len = 2;
+                              SLsmg_write_nstring(text, len);
+                              text = text + len;
+                      }
(that is: the nested ifs are completely bogus (the first is always true,
the second and third are always false)).

I haven't looked at the surrounding code and just guess that text is
supposed to point at an UTF-8 text, so the following may be as bogus
as the original patch.

It's nice that Czech will work now, but what about the languages
which use more than 11 bits (2 UTF-8 chars) of character code space?

FWIW, the right way to test UTF-8 character length:
len = 1;
// if ((*text & 0xC0) == 0x80) CHAR_IS_BOGUS; else
if ((*text & 0xC0) == 0xC0)
  {
    if (*text < 0xE0) len = 2;
    else if (*text < 0xF0) len = 3;
    else if (*text < 0xF8) len = 4;
    // and so on
  }
Not to mention that the maximal length of UTF-8 character is 6, not 4 as
in the patch.