history update
(cherry picked from commit ed9e47a1a6dad652a7ea292d39339d783c853069)
ARM JIT: fix software floating-point

I broke uses of LDRD and STRD when compacting the set of registers
used by the JIT. The LDRD and STRD instructions are given one
register explicitly, but they implicitly use the next regsister, too,
and the specified register must be even-numbered. Lining up a pair of
registers requires a little shuffling before and after the operation.

Also, the LDRDI and STRD encodings were broken, and the inlined
fl->fx conversion was not right.

Closes PR 14470
(cherry picked from commit ffb0dd52c5428f379318b7e9470530e235059d38)
fix clean-up handling for the main thread of a terminated place

This bug might be reposnible for the occassional crashes seen in
DrDr for the easter-egg test.

Merge to v6.0.1
(cherry picked from commit 83dcf446a342b6dd903f4419af4249f771352296)