EABI x Zce issues to be straightened

[jnk0le]

made some issues regarding EABI in Zce and its fragmentation
riscvarchive/riscv-code-size-reduction/issues/174
riscvarchive/riscv-code-size-reduction#176 <- XLEN alignment like in ILP32E will be even more problematic

I think that some missasumptions about Zcmpe/eabi fragmentation needs to be straightened before Zcmp gets frozen

note that eabi part of Zce is not being frozen/ratified now, but may end up with awful encodings due to bad rlist allocation