[WIP] Tests which use NDK native tools must target API 19 at least

Author: grendello

src/Xamarin.Android.Build.Tasks/Tasks/GetAotArguments.cs

@@ -137,13 +137,17 @@ int GetNdkApiLevel (NdkTools ndk, AndroidTargetArch arch)
 			int level;
 			if (manifest?.MinSdkVersion != null) {
 				level       = manifest.MinSdkVersion.Value;
+				Log.LogDebugMessage ($"NDK API level read from manifest");
 			} else if (int.TryParse (MinimumSupportedApiLevel, out level)) {
+				Log.LogDebugMessage ("NDK API level taken from MinimumSupportedApiLevel");
 				// level already set
 			} else if (int.TryParse (AndroidApiLevel, out level)) {
+				Log.LogDebugMessage ("NDK API level taken from AndroidApiLevel");
 				// level already set
 			} else {
 				// Probably not ideal!
 				level       = MonoAndroidHelper.SupportedVersions.MaxStableVersion.ApiLevel;
+				Log.LogDebugMessage ("NDK API level taken from MonoAndroidHelper.SupportedVersions.MaxStableVersion.ApiLevel");
 			}
 
 			// Some Android API levels do not exist on the NDK level. Workaround this my mapping them to the
@@ -157,6 +161,7 @@ int GetNdkApiLevel (NdkTools ndk, AndroidTargetArch arch)
 
 			// API levels below level 21 do not provide support for 64-bit architectures.
 			if (ndk.IsNdk64BitArch (arch) && level < 21) {
+				Log.LogDebugMessage ("NDK API level raised to 21, required for 64-bit support");
 				level = 21;
 			}
 
@@ -172,6 +177,7 @@ int GetNdkApiLevel (NdkTools ndk, AndroidTargetArch arch)
 				}
 			}
 
+			Log.LogDebugMessage ($"Using NDK API level {level}");
 			return level;
 		}