Missing coverage for compressed illegal instruction

[Bill94l]

Hi,
For some compressed instructions, the non-zero check for the RS/RD registers and the immediate value is missing. Here is the list of instructions with the associated missing checks:

• C.ADDI4SPN : imm != 0
• C.ADDIW : rd != 0
• C.LII : imm != 0
• C.LWSP : rd != 0
• C.LDSP : rd != 0
• C.JR : rs != 0