Make apex availability of some bionic libraries explicit

The libraries are
- libdl_static
- liblinker_main
- liblinker_malloc
- libsystemproperties

The availability to runtime apex was done implicitly using a baseline map in
build/soong/apex/apex.go. Make this explicit in Android.bp

Bug: 281077552
Test: m nothing
Change-Id: I029ae204f6cfef8c301a20b7c4294636b60b38be
diff --git a/linker/Android.bp b/linker/Android.bp
index 2ca962a..4787d87 100644
--- a/linker/Android.bp
+++ b/linker/Android.bp
@@ -146,12 +146,18 @@
 
     // Ensure that the compiler won't insert string function calls before ifuncs are resolved.
     cflags: ["-ffreestanding"],
+    apex_available: [
+        "com.android.runtime",
+    ],
 }
 
 cc_library_static {
     name: "liblinker_malloc",
     defaults: ["linker_defaults", "linker_all_targets"],
     srcs: ["linker_memory.cpp"],
+    apex_available: [
+        "com.android.runtime",
+    ],
 }
 
 cc_library_static {