MFC r233100:

MFC r233100:
In vm_object_page_clean(), do not clean OBJ_MIGHTBEDIRTY object flag
if the filesystem performed short write and we are skipping the page
due to this.

Propogate write error from the pager back to the callers of
vm_pageout_flush().  Report the failure to write a page from the
requested range as the FALSE return value from vm_object_page_clean(),
and propagate it back to msync(2) to return EIO to usermode.

While there, convert the clearobjflags variable in the
vm_object_page_clean() and arguments of the helper functions to
boolean.

PR:	kern/165927

git-svn-id: svn://svn.freebsd.org/base/stable/9@233728 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f