x86_32: legalize br{z,nz}.i64.

cranelift/filetests/filetests/isa/x86/brz-x86_32-i64.clif

@@ -0,0 +1,36 @@
+test compile
+target i686
+
+function u0:0(i32, i32) -> i32 {
+block0(v0: i32, v1: i32):
+    v2 = iconcat v0, v1
+    ; check:      v6 = fill v0
+    ; nextln:     v3 = icmp_imm eq v6, 0
+    ; nextln:     v7 = fill v1
+    ; nextln:     v4 = icmp_imm eq v7, 0
+    ; nextln:     v5 = band v3, v4
+    ; nextln:     brnz v5, block1
+    brz v2, block1
+    jump block2
+block1:
+    trap unreachable
+block2:
+    trap unreachable
+}
+
+function u0:1(i32, i32) -> i32 {
+block0(v0: i32, v1: i32):
+    v2 = iconcat v0, v1
+    ; check:      v3 = fill v0
+    ; nextln:     brnz v3, block1
+    ; nextln:     fallthrough block3
+    ; check:  block3:
+    ; nextln:     v4 = fill.i32 v1
+    ; nextln:     brnz v4, block1
+    brnz v2, block1
+    jump block2
+block1:
+    trap unreachable
+block2:
+    trap unreachable
+}