amd64/arm64 pmap: consistently clear PGA_WRITEABLEHEADmain

We don't consistently clear PGA_WRITEABLE on fictitious, managed pages.
Some functions do, e.g., pmap_remove_all(), but several do not.  At
worst, this is just a pessimization, but there is no good reason to be
inconsistent.  Clear PGA_WRITEABLE in those that previously did not by
introducing (and using) the helper function pmap_page_is_mapped_locked()
that implements the correct test.

Reviewed by:	kib, markj
MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D59466

0 files changed, 0 insertions, 0 deletions