tree-wide: make ++/-- usage consistent WRT spacing

Throughout the tree there's spurious use of spaces separating ++ and --
operators from their respective operands.  Make ++ and -- operator
consistent with the majority of existing uses; discard the spaces.

src/basic/utf8.c

@@ -241,7 +241,7 @@ char *utf8_escape_non_printable(const char *str) {
                                         *(s++) = hexchar((int) *str);
 
                                         str += 1;
-                                        len --;
+                                        len--;
                                 }
                         }
                 } else {