Add libdl_android as a bootstrap library.

Necessary after moving it into the Runtime APEX, as several framework
libraries loaded during early boot depends on it, e.g. libvndksupport.so,
libvulkan.so, and libgraphicsenv.so.

Test: build & boot
Bug: 135753770
Change-Id: I5862ba57485bdaffd452aac47c5931863823075d
diff --git a/target/product/base_system.mk b/target/product/base_system.mk
index 2fd0312..1c9c879 100644
--- a/target/product/base_system.mk
+++ b/target/product/base_system.mk
@@ -126,6 +126,7 @@
     libcamera2ndk \
     libcutils \
     libdl.bootstrap \
+    libdl_android.bootstrap \
     libdrmframework \
     libdrmframework_jni \
     libEGL \