Googletest export

Remove last traces of gtest-linked_ptr.h

PiperOrigin-RevId: 219164781
diff --git a/googletest/Makefile.am b/googletest/Makefile.am
index b84a837..88620d8 100644
--- a/googletest/Makefile.am
+++ b/googletest/Makefile.am
@@ -199,7 +199,6 @@
   include/gtest/internal/gtest-death-test-internal.h \
   include/gtest/internal/gtest-filepath.h \
   include/gtest/internal/gtest-internal.h \
-  include/gtest/internal/gtest-linked_ptr.h \
   include/gtest/internal/gtest-param-util-generated.h \
   include/gtest/internal/gtest-param-util.h \
   include/gtest/internal/gtest-port.h \