Update GN files w/ changes needed to make sanitizers work.

build/config/BUILDCONFIG.gn

Index: build/config/BUILDCONFIG.gn
diff --git a/build/config/BUILDCONFIG.gn b/build/config/BUILDCONFIG.gn
index 86fceae3a3b4f7ce5fcbc8551387a359919faf82..84109073f8c0c8f105c54e6bd737b7ed71cf723b 100644
--- a/build/config/BUILDCONFIG.gn
+++ b/build/config/BUILDCONFIG.gn
@@ -511,13 +511,22 @@ if (is_win) {
 }
 
 # Executable defaults.
-_executable_configs = _native_compiler_configs + [
-                        "//build/config:default_libs",
-                        "//build/config:executable_config",
-                      ]
+_executable_configs =
+    _native_compiler_configs + [
+      "//build/config:default_libs",
+      "//build/config:executable_config",
+
+      # If we're using the prebuilt instrumented libraries with the
+      # sanitizers, we need to add ldflags to every binary to make sure
+      # they are picked up. We can't check for using_sanitizer in BUILDCONFIG,
+      # so we add the config unconditionally and have it be empty when not
+      # using the libraries.
+      "//third_party/instrumented_libraries:prebuilt_instrumented_libraries_ldflags",
+    ]
 if (is_win) {
   _executable_configs += _windows_linker_configs
 }
+
 set_defaults("executable") {
   configs = _executable_configs
 }
@@ -529,10 +538,12 @@ set_defaults("static_library") {
 
 # Shared library and loadable module defaults (also for components in component
 # mode).
-_shared_library_configs = _native_compiler_configs + [
-                            "//build/config:default_libs",
-                            "//build/config:shared_library_config",
-                          ]
+_shared_library_configs =
+    _native_compiler_configs + [
+      "//build/config:default_libs",
+      "//build/config:shared_library_config",
+      "//third_party/instrumented_libraries:prebuilt_link_helper",
+    ]
 if (is_win) {
   _shared_library_configs += _windows_linker_configs
 } else if (is_android) {