Recent changes to 39: Use mkstemp instead of tmpnam

Recent changes to 39: Use mkstemp instead of tmpnamhttps://sourceforge.net/p/mathgl/bugs/39/2018-01-05T20:46:23.356000ZRecent changes to 39: Use mkstemp instead of tmpnamUse mkstemp instead of tmpnam2018-01-05T20:46:23.356000Z2018-01-05T20:46:23.356000ZAnonymoushttps://sourceforge.net/u/userid-None/https://sourceforge.net7fab9a3291b54e79d2f25e1935bcc5ae8812df67

<div class="markdown_content"><p>export.cpp:(.text+0x1bc9): warning: the use of <code>tmpnam' is dangerous, better use</code>mkstemp'</p></div>