[gn build] Port a06073f

Author: aeubanks

llvm/utils/gn/secondary/libcxx/include/BUILD.gn

@@ -928,6 +928,7 @@ if (current_toolchain == default_toolchain) {
       "__utility/in_place.h",
       "__utility/integer_sequence.h",
       "__utility/is_pointer_in_range.h",
+      "__utility/is_valid_range.h",
       "__utility/move.h",
       "__utility/no_destroy.h",
       "__utility/pair.h",