Allow spoofing signingInfo for microG Companion/Services

- Spoof PackageInfo signingInfo + signatures so that
  G suite apps do not complain anymore.

Change-Id: I86f182c9e1d18b0e997803842577a90ef740cfd1
Signed-off-by: althafvly <althafvly@gmail.com>

services/core/java/com/android/server/pm/ComputerEngine.java

@@ -168,6 +168,7 @@
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.nio.charset.StandardCharsets;
+import java.security.cert.CertificateException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -1588,6 +1589,18 @@ public final PackageInfo generatePackageInfo(PackageStateInternal ps,
 
             generateFakeSignature(p).ifPresent(fakeSignature -> {
                 packageInfo.signatures = new Signature[]{fakeSignature};
+                try {
+                    packageInfo.signingInfo = new SigningInfo(
+                            new SigningDetails(
+                                    packageInfo.signatures,
+                                    SigningDetails.SignatureSchemeVersion.SIGNING_BLOCK_V3,
+                                    SigningDetails.toSigningKeys(packageInfo.signatures),
+                                    null
+                            )
+                    );
+                } catch (CertificateException e) {
+                    Slog.e(TAG, "Caught an exception when creating signing keys: ", e);
+                }
             });
 
             return packageInfo;