linker: Add support for "whitelisted" property in linker config files

In order to enable no-vendor-variant VNDK, we need a way to restrict a
namespace to only a list of whitelisted libraries.  We add a new
"whitelisted" property for this.  If the property is not set, all
libraries in the search paths are available in a namespace.  If the
property is set, only the libraries named are available.

Bug: 119423884
Test: Boot with no-vendor-variant VNDK enabled using the new property.
Change-Id: Id808c1733c8e2c2c3462b04c72461f9698403571
diff --git a/linker/linker_config.cpp b/linker/linker_config.cpp
index f7f9c41..437aa86 100644
--- a/linker/linker_config.cpp
+++ b/linker/linker_config.cpp
@@ -552,6 +552,12 @@
     ns_config->set_isolated(properties.get_bool(property_name_prefix + ".isolated"));
     ns_config->set_visible(properties.get_bool(property_name_prefix + ".visible"));
 
+    std::string whitelisted =
+        properties.get_string(property_name_prefix + ".whitelisted", &lineno);
+    if (!whitelisted.empty()) {
+      ns_config->set_whitelisted_libs(android::base::Split(whitelisted, ":"));
+    }
+
     // these are affected by is_asan flag
     if (is_asan) {
       property_name_prefix += ".asan";