Add support for Android 11 RefBase ABI (#29)

Implements a compatibility layer to allow the binary to run on
Android 11 (API 30) and older, which lack the `incStrongRequireStrong`
symbol in their `libutils.so`.

This is achieved by creating a runtime wrapper that checks the device's
SDK version.
- On Android 12 (API 31) and newer, it dynamically loads and calls the
  `incStrongRequireStrong` function using `dlsym`.
- On older versions, it safely falls back to the universally available
  `incStrong` method.

This resolves the fatal `dlopen` error "cannot locate symbol" when
injecting the library into processes on older Android versions.

See AOSP change
https://android-review.googlesource.com/c/platform/system/core/+/1660499

app/src/main/cpp/external/AOSP/include/utils/StrongPointer.h

@@ -17,6 +17,7 @@
 #ifndef ANDROID_STRONG_POINTER_H
 #define ANDROID_STRONG_POINTER_H
 
+#include "refbase_compat.h"
 #include <functional>
 #include <type_traits>  // for common_type.
 
@@ -212,7 +213,7 @@ sp<T> sp<T>::make(Args&&... args) {
 template <typename T>
 sp<T> sp<T>::fromExisting(T* other) {
     if (other) {
-        other->incStrongRequireStrong(other);
+        incStrongFromExisting(other, other);
         sp<T> result;
         result.m_ptr = other;
         return result;