src/etc/mingw-fix-include/README.txt

   1 The purpose of these headers is to fix issues with mingw v4.0, as described in #9246.
   2
   3 This works by adding this directory to GCC include search path before mingw system headers directories,
   4 so we can intercept their inclusions and add missing definitions without having to modify files in mingw/include.
   5
   6 Once mingw fixes all 3 issues mentioned in #9246, this directory and all references to it from rust/mk/* may be removed.