cranelift: Implement icmp for scalar types

Add `icmp` tests for all scalar types and condition codes.

AArch64 (no)overflow tests are disabled because they are currently failing.

cranelift/filetests/filetests/runtests/icmp-sge.clif

@@ -0,0 +1,53 @@
+test interpret
+test run
+target aarch64
+target x86_64 machinst
+
+
+function %icmp_sge_i8(i8, i8) -> b1 {
+block0(v0: i8, v1: i8):
+    v2 = icmp sge v0, v1
+    return v2
+}
+; run: %icmp_sge_i8(0, 0) == true
+; run: %icmp_sge_i8(1, 0) == true
+; run: %icmp_sge_i8(-1, -1) == true
+; run: %icmp_sge_i8(0, 1) == false
+; run: %icmp_sge_i8(-5, -1) == false
+; run: %icmp_sge_i8(1, -1) == true
+
+function %icmp_sge_i16(i16, i16) -> b1 {
+block0(v0: i16, v1: i16):
+    v2 = icmp sge v0, v1
+    return v2
+}
+; run: %icmp_sge_i16(0, 0) == true
+; run: %icmp_sge_i16(1, 0) == true
+; run: %icmp_sge_i16(-1, -1) == true
+; run: %icmp_sge_i16(0, 1) == false
+; run: %icmp_sge_i16(-5, -1) == false
+; run: %icmp_sge_i16(1, -1) == true
+
+function %icmp_sge_i32(i32, i32) -> b1 {
+block0(v0: i32, v1: i32):
+    v2 = icmp sge v0, v1
+    return v2
+}
+; run: %icmp_sge_i32(0, 0) == true
+; run: %icmp_sge_i32(1, 0) == true
+; run: %icmp_sge_i32(-1, -1) == true
+; run: %icmp_sge_i32(0, 1) == false
+; run: %icmp_sge_i32(-5, -1) == false
+; run: %icmp_sge_i32(1, -1) == true
+
+function %icmp_sge_i64(i64, i64) -> b1 {
+block0(v0: i64, v1: i64):
+    v2 = icmp sge v0, v1
+    return v2
+}
+; run: %icmp_sge_i64(0, 0) == true
+; run: %icmp_sge_i64(1, 0) == true
+; run: %icmp_sge_i64(-1, -1) == true
+; run: %icmp_sge_i64(0, 1) == false
+; run: %icmp_sge_i64(-5, -1) == false
+; run: %icmp_sge_i64(1, -1) == true