cmd/gogio: bump minimum Android SDK version to 17 (Android 4.2)

The CPU fallback renderer relies on posix_memalign, which was exposed in
Android 4.2. Support for Android 4.1 could be restored by writing
posix_memalign outselves, but this change is easier.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

cmd/gogio/androidbuild.go

@@ -192,7 +192,7 @@ func compileAndroid(tmpDir string, tools *androidTools, bi *buildInfo) (err erro
 	if err != nil {
 		return err
 	}
-	minSDK := 16
+	minSDK := 17
 	if bi.minsdk > minSDK {
 		minSDK = bi.minsdk
 	}