Replace $(call my-dir) with a string literal

This is so that we can set LOCAL_PATH to the result
of my-dir, as LOCAL_PATH can only be set to a string
literal of the exact value of LOCAL_PATH.

It's probably also the correct choice to start phasing
out LOCAL_PATH.

Bug: 214405650
Test: go test
Change-Id: Ia97d7fedf4ce62643921d90a176e65edd4e2fce6
diff --git a/mk2rbc/variable.go b/mk2rbc/variable.go
index 506266a..be1b174 100644
--- a/mk2rbc/variable.go
+++ b/mk2rbc/variable.go
@@ -319,15 +319,13 @@
 			v = &localVariable{baseVariable{nam: name, typ: hintType}}
 		} else {
 			vt := hintType
-			if strings.HasPrefix(name, "LOCAL_") && vt == starlarkTypeUnknown {
-				// Heuristics: local variables that contribute to corresponding config variables
-				if cfgVarName, found := localProductConfigVariables[name]; found {
-					vi, found2 := KnownVariables[cfgVarName]
-					if !found2 {
-						panic(fmt.Errorf("unknown config variable %s for %s", cfgVarName, name))
-					}
-					vt = vi.valueType
+			// Heuristics: local variables that contribute to corresponding config variables
+			if cfgVarName, found := localProductConfigVariables[name]; found && vt == starlarkTypeUnknown {
+				vi, found2 := KnownVariables[cfgVarName]
+				if !found2 {
+					panic(fmt.Errorf("unknown config variable %s for %s", cfgVarName, name))
 				}
+				vt = vi.valueType
 			}
 			if strings.HasSuffix(name, "_LIST") && vt == starlarkTypeUnknown {
 				// Heuristics: Variables with "_LIST" suffix are lists