Rename intel to x86.

x86 is the more accurate name, as there are non-Intel x86 implementations.

Fixes #263.

cranelift/filetests/isa/x86/legalize-mulhi.cton

@@ -0,0 +1,45 @@
+
+test compile
+set is_64bit
+isa x86 baseline
+
+; umulhi/smulhi on 64 bit operands
+
+function %i64_umulhi(i64, i64) -> i64 {
+ebb0(v10: i64, v11: i64):
+  v12 = umulhi v10, v11
+  ; check: %rdi -> %rax
+  ; check: x86_umulx
+  ; check: %rdx -> %rax
+  return v12
+}
+
+function %i64_smulhi(i64, i64) -> i64 {
+ebb0(v20: i64, v21: i64):
+  v22 = smulhi v20, v21
+  ; check: %rdi -> %rax
+  ; check: x86_smulx
+  ; check: %rdx -> %rax
+  return v22
+}
+
+
+; umulhi/smulhi on 32 bit operands
+
+function %i32_umulhi(i32, i32) -> i32 {
+ebb0(v30: i32, v31: i32):
+  v32 = umulhi v30, v31
+  ; check: %rdi -> %rax
+  ; check: x86_umulx
+  ; check: %rdx -> %rax
+  return v32
+}
+
+function %i32_smulhi(i32, i32) -> i32 {
+ebb0(v40: i32, v41: i32):
+  v42 = smulhi v40, v41
+  ; check: %rdi -> %rax
+  ; check: x86_smulx
+  ; check: %rdx -> %rax
+  return v42
+}