Move charsToString to architecture dependent source to fix casting problem

Signed-off-by: Stefan Scherer <scherer_stefan@icloud.com>

pkg/platform/architecture_linux.go

@@ -14,15 +14,3 @@ func GetRuntimeArchitecture() (string, error) {
 	}
 	return charsToString(utsname.Machine), nil
 }
-
-func charsToString(ca [65]int8) string {
-	s := make([]byte, len(ca))
-	var lens int
-	for ; lens < len(ca); lens++ {
-		if ca[lens] == 0 {
-			break
-		}
-		s[lens] = uint8(ca[lens])
-	}
-	return string(s[0:lens])
-}

pkg/platform/utsname_int8.go

@@ -0,0 +1,18 @@
+// +build linux,386 linux,amd64 linux,arm64
+// see golang's sources src/syscall/ztypes_linux_*.go that use int8
+
+package platform
+
+// Convert the OS/ARCH-specific utsname.Machine to string
+// given as an array of signed int8
+func charsToString(ca [65]int8) string {
+	s := make([]byte, len(ca))
+	var lens int
+	for ; lens < len(ca); lens++ {
+		if ca[lens] == 0 {
+			break
+		}
+		s[lens] = uint8(ca[lens])
+	}
+	return string(s[0:lens])
+}

pkg/platform/utsname_uint8.go

@@ -0,0 +1,18 @@
+// +build linux,arm linux,ppc64 linux,ppc64le s390x
+// see golang's sources src/syscall/ztypes_linux_*.go that use uint8
+
+package platform
+
+// Convert the OS/ARCH-specific utsname.Machine to string
+// given as an array of unsigned uint8
+func charsToString(ca [65]uint8) string {
+	s := make([]byte, len(ca))
+	var lens int
+	for ; lens < len(ca); lens++ {
+		if ca[lens] == 0 {
+			break
+		}
+		s[lens] = ca[lens]
+	}
+	return string(s[0:lens])
+}