Upgrade to version 1.0.0rc5.5

[jeremybennett]

The latest version makes some changes to the current work. See specification draft 1.0.0rv5.5.

[pz9115]

Proposal from specification change:

• [ ] Remove zcmb extension, since the benefit is low, keep zcb extension only.
• [ ] Add zcd extension refer to compressed double-precision floating-point load/stores
• [ ] Zcf now limit on RV32 only
• [ ] Check zcb implyment and add them
• [ ] Check cm.jalt changes and update it

[pz9115]

New upgrade to version 1.0.0rc5.6:

See specification draft 1.0.0rv5.6.

• [ ] remove zcmpe extension

[tariqkurd-repo]

note the cm.jt/cm.jalt split has changed

[jeremybennett]

This is the subject of https://github.com/openhwgroup/corev-binutils-gdb/pull/65, currently under review

[jeremybennett]

65 has now been merged, so this can be closed.