add missing fwd decl for struct _DISK_GEOMETRY_EX

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6429 4407c894-4637-0410-b4f5-ada5f102cad1
add missing fwd decl for struct _DISK_GEOMETRY_EX

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6430 4407c894-4637-0410-b4f5-ada5f102cad1
Fix issue found by Antony Riakiotakis related to mutex-destroy.
We returned wrongly EBUSY state for unlocked mutexes on destruction, when
internal spin-guard is busy.  EBUSY has only to be returned if to be destroyed mutex has a lock.



git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6431 4407c894-4637-0410-b4f5-ada5f102cad1
merge of r6414 through r6431 into 'src/mutex.c'

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6432 4407c894-4637-0410-b4f5-ada5f102cad1