runtime: add proper arm arch

src/runtime/arch_arm.go

@@ -0,0 +1,11 @@
+// +build arm
+
+package runtime
+
+const GOARCH = "arm"
+
+// The length type used inside strings and slices.
+type lenType uint32
+
+// The bitness of the CPU (e.g. 8, 32, 64).
+const TargetBits = 32

src/runtime/arch_wasm.go

@@ -1,4 +1,4 @@
-// +build wasm,!avr
+// +build wasm,!arm,!avr
 
 package runtime