mingw patch for mkdir()

[wrotycz]

In (c)lzip definition of mkdir takes 2 arguments while in windows it takes 1, which causes compilation error.

```

gcc  -Wall -W -O2 -DPROGVERSION=\"1.14\" -c -o main.o main.c

main.c: In function 'make_dirs':

main.c:527:16: error: too many arguments to function 'mkdir'

  527 |       else if( mkdir( partial, mode ) != 0 && errno != EEXIST )

      |                ^~~~~

```

It can be solved by defining macro in "windows" section.

```

diff clzip-1.14/main.c clzip-1.14-mkdir/main.c

43a44

> #define mkdir(x,y) mkdir(x)

```

Same for lzip.

```

diff lzip-1.24/main.cc lzip-1.24-mkdir/main.cc

46a47

> #define mkdir(x,y) mkdir(x)

```

Same for plzip but didn't check it yet.

FWIW I have built clzip with that patch to prove a concept and to share it. It's available here: www.mediafire.com/file/l7r8cvi2gbx9f9s/clzip-1.14_w32-1.zip .

It's no lzip as it would require static link of whole libstdc++ which is unnecessary as C version is just as fast.

Speaking of speed decoder seems to be faster when compiled with `-O3' optimization. Also decoder is faster compiled with GCC and encoder compiled with Clang.