Revert "linker: disable ld.config.txt in ASAN mode"

This reverts commit 81b175747d.

Reason: 02586a2a34 fixed the bug that
prevented us from using LD_PRELOAD with multiple namespaces.

Bug: 38114603
Test: 1. ./external/compiler-rt/lib/asan/scripts/asan_device_setup --lib
prebuilts/clang/host/linux-x86/clang-stable/lib64/clang/5.0/lib/linux
2. enable talkback shortcut
3. in the home screen, hold vol-up/down together
4. device does not reboots and talkback shortcut is toggled
Test: bionic-unit-tests and linker-unit-tests successful

(cherry picked from commit 6ab40bbf53)

Merged-In: I25a05927ffbb28b9fa72303652893f43918ccec6
Change-Id: If264f0ce5d7187816d3acc790b6e31d479b628ee

linker/linker_config.cpp

@@ -375,15 +375,6 @@ bool Config::read_binary_config(const char* ld_config_file_path,
                                       bool is_asan,
                                       const Config** config,
                                       std::string* error_msg) {
-  // TODO(b/38114603) Currently, multiple namespaces does not support ASAN mode
-  // where some symbols should be intercepted via LD_PRELOAD; LD_PRELOADed libs
-  // are not being preloaded into the linked namespaces other than the default
-  // namespace. Until we fix the problem, we temporarily disable ld.config.txt
-  // in ASAN mode.
-  if (is_asan) {
-    return false;
-  }
-
   g_config.clear();
 
   std::unordered_map<std::string, PropertyValue> property_map;

linker/tests/linker_config_test.cpp

@@ -168,7 +168,6 @@ TEST(linker_config, smoke) {
   run_linker_config_smoke_test(false);
 }
 
-// TODO(b/38114603) revive this test when ld.config.txt is enabled for ASAN mode
-//TEST(linker_config, asan_smoke) {
-//  run_linker_config_smoke_test(true);
-//}
+TEST(linker_config, asan_smoke) {
+  run_linker_config_smoke_test(true);
+}