Add SCP support for Android files

SCP uses the JNI headers in generated code, so several targets need
the include path; this will have no effect on non-SCP builds.  Also,
in "protected" builds, there is a generated library that needs to be
linked in the final binary, but this doesn't exist in the "analysis"
step; we create an empty static library if it doesn't exist so it works
on all cases.

Merged from https://widevine-internal-review.googlesource.com/169850

Merged from https://widevine-internal-review.googlesource.com/176177

Bug: 262635528
Change-Id: Ib676d55efbcbec81de9c3123bc70afb570d6caa5
(cherry picked from commit b9482eb23c261788a4432de7566f1b1de1cf9379)

libwvdrmengine/cdm/Android.bp

@@ -38,7 +38,10 @@ cc_library_static {
         "external/protobuf/src",
     ],
 
-    header_libs: ["libutils_headers"],
+    header_libs: [
+        "jni_headers",
+        "libutils_headers",
+    ],
 
     static_libs: ["libcdm_protos"],
     shared_libs: ["libcrypto"],