Add support for the Zicond ISA extension

This patch intoduces a coverage model and the generated
test cases using riscv_ctg.

The tests have been generated using the following command:
  riscv_ctg.py \
    --cgf coverage/dataset.cgf \
    --cgf coverage/zicond.cgf \
    -bi rv32i \
    -d tests/
  riscv_ctg.py \
    --cgf coverage/dataset.cgf \
    --cgf coverage/zicond.cgf \
    -bi rv64i \
    -d tests64/

The resulting tests have been copied to the target directory:
  cp tests/*S riscv-test-suite/rv32i_m/Zicond/src/
  cp tests64/*S riscv-test-suite/rv64i_m/Zicond/src/

This PR depends on Zicond support in the riscv-ctg repo:
  riscv-software-src/riscv-ctg#59

Signed-off-by: Christoph Müllner <[email protected]>

coverage/zicond.cgf

@@ -0,0 +1,37 @@
+czero.eqz:
+    config: 
+      - check ISA:=regex(.*Zicond.*)
+    opcode: 
+      czero.eqz: 0
+    rs1: 
+      <<: *all_regs
+    rs2: 
+      <<: *all_regs
+    rd: 
+      <<: *all_regs
+    op_comb: 
+      <<: *rfmt_op_comb
+    val_comb:
+      <<: [*base_rs1val_sgn , *base_rs2val_sgn , *rfmt_val_comb_sgn]
+      abstract_comb:
+        'sp_dataset(xlen)': 0
+        <<: [*rs1val_walking, *rs2val_walking]
+
+czero.nez:
+    config: 
+      - check ISA:=regex(.*Zicond.*)
+    opcode: 
+      czero.nez: 0
+    rs1: 
+      <<: *all_regs
+    rs2: 
+      <<: *all_regs
+    rd: 
+      <<: *all_regs
+    op_comb: 
+      <<: *rfmt_op_comb
+    val_comb:
+      <<: [*base_rs1val_sgn , *base_rs2val_sgn , *rfmt_val_comb_sgn]
+      abstract_comb:
+        'sp_dataset(xlen)': 0
+        <<: [*rs1val_walking, *rs2val_walking]