For amd64 non-PCID machines, and for i386 machines with support for

For amd64 non-PCID machines, and for i386 machines with support for
the PG_G global pte flag, pmap_invalidate_all() fails to flush global
TLB entries [*].  This is because TLB shootdown handler for such
configs reloads CR3, and on i386 pmap_invalidate_all() does the same
for the initiating CPU.  Note that current code does not issue total
invalidation requests for the kernel_pmap.

Rename amd64 function invltlb_globpcid() to invltlb_glob(), it is not
specific for PCID for quite some time, and implement the same
functionality for i386.  Use the function instead of invltlb() in
shootdown handlers and in i386 pmap_invalidate_all(), but only for the
kernel pmap (which maps pages with the PG_G attribute set), which
takes care of PG_G TLB entries on flush.

To detect the affected pmap in i386 TLB shootdown handler, pmap should
be passed to the smp_masked_invltlb() function, which makes amd64 and
i386 TLB shootdown code almost identical.  Merge the code under x86/.

Noted by:	jhb [*]
Reviewed by:	cem, jhb, pho
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D4346