Avoid re-defining uint32_t when using mingw compiler

Avoid re-defining uint32_t when using mingw compiler

Since MingW for quite a long time (since 3.2 in 2008?) has defined
'uint32_t' etc. in it's <stdint.h>, we need to guard against defining
them again. Ideally we should figure out in what version of MingW
this happened. But for now:

Signed-off-by: Gisle Vanem <gvanem@broadpark.no>
Acked-by: David Sommerseth <dazo@users.sourceforge.net>
Signed-off-by: David Sommerseth <dazo@users.sourceforge.net>