tdf#116394 writerfilter: append '=' if not a formula marker

Oops - a silly mistake to throw away the character if
it didn't match a special purpose.

There is no point in adding a unit test for this.

Change-Id: I3b48af578ae96744405ec0919ff341d1c9b43f65
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/109426
Tested-by: Jenkins
Reviewed-by: Justin Luth <justin_luth@sil.org>
(cherry picked from commit b232b422a3cfe3b410bbc75e0fffdfc238fd10e7)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/109398
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>
diff --git a/writerfilter/source/dmapper/DomainMapper_Impl.cxx b/writerfilter/source/dmapper/DomainMapper_Impl.cxx
index 7a248ca..d0d5a9f 100644
--- a/writerfilter/source/dmapper/DomainMapper_Impl.cxx
+++ b/writerfilter/source/dmapper/DomainMapper_Impl.cxx
@@ -3387,6 +3387,8 @@ static OUString lcl_ExtractToken(OUString const& rCommand,
                    ++rIndex;
                    return "FORMULA";
                }
                else
                    token.append('=');
            break;
            default:
                token.append(currentChar);