Apex: support codenames for min_sdk_version

Apex can use codenames like "Q", "R" for its min_sdk_version property.
Also, cc_library can use codenames for its stubs.versions.

Bug: 152655956
Test: m
Merged-In: I077ad7b2ac5d90b4c8708921e43846206f05ba70
Change-Id: I077ad7b2ac5d90b4c8708921e43846206f05ba70
(cherry picked from commit 29e91d21219485f0bc675c4d6034b5726be4ca92)
diff --git a/apex/apex.go b/apex/apex.go
index 2370acc..46ccc50 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -20,7 +20,6 @@
 	"path/filepath"
 	"regexp"
 	"sort"
-	"strconv"
 	"strings"
 	"sync"
 
@@ -1808,14 +1807,11 @@
 
 func (a *apexBundle) minSdkVersion(ctx android.BaseModuleContext) int {
 	ver := proptools.StringDefault(a.properties.Min_sdk_version, "current")
-	if ver != "current" {
-		minSdkVersion, err := strconv.Atoi(ver)
-		if err != nil {
-			ctx.PropertyErrorf("min_sdk_version", "should be \"current\" or <number>, but %q", ver)
-		}
-		return minSdkVersion
+	intVer, err := android.ApiStrToNum(ctx, ver)
+	if err != nil {
+		ctx.PropertyErrorf("min_sdk_version", "%s", err.Error())
 	}
-	return android.FutureApiLevel
+	return intVer
 }
 
 // A regexp for removing boilerplate from BaseDependencyTag from the string representation of