bug#13079: 24.3.50; Emacs cannot create subprocess

[Li Zhai]

I got it. The maximize number of calling mktemp is 42 if we don't
remove the temporary em* files.

I found a very interesting discuss about the limit of mktemp on windows.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47439

They implement a new mktemp function to walk around the limit on the
number of concurrently open files.

Can we implement our mktemp functions instead of using microsoft's stuff?