[gn build] Port 59e66c5

Author: aeubanks

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

@@ -466,6 +466,7 @@ if (current_toolchain == default_toolchain) {
       "__format/formatter_pointer.h",
       "__format/formatter_string.h",
       "__format/formatter_tuple.h",
+      "__format/indic_conjunct_break_table.h",
       "__format/parser_std_format_spec.h",
       "__format/range_default_formatter.h",
       "__format/range_formatter.h",