container/check: move absolute pathname

This allows use of absolute pathname values without importing container.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/comp.go

@@ -6,11 +6,11 @@ var (
 	version = compPoison
 )
 
-// check validates string value set at compile time.
-func check(s string) (string, bool) { return s, s != compPoison && s != "" }
+// checkComp validates string value set at compile time.
+func checkComp(s string) (string, bool) { return s, s != compPoison && s != "" }
 
 func Version() string {
-	if v, ok := check(version); ok {
+	if v, ok := checkComp(version); ok {
 		return v
 	}
 	return "impure"