[LyX/master] Support C++98 again (gcc 4.8).

[Pavel Sanda]

commit d6b108d8c341699e7bece63fc046b8a82c8b1e2d
Author: Pavel Sanda <sanda at lyx.org>
Date:   Wed Nov 6 15:54:27 2019 +0100

    Support C++98 again (gcc 4.8).
---
 src/tex2lyx/Preamble.cpp |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/tex2lyx/Preamble.cpp b/src/tex2lyx/Preamble.cpp
index 3e2fa67..38139b4 100644
--- a/src/tex2lyx/Preamble.cpp
+++ b/src/tex2lyx/Preamble.cpp
@@ -1175,7 +1175,7 @@ void Preamble::handle_package(Parser &p, string const & name,
 	if (is_known(name, known_sans_font_packages)) {
 		h_font_sans[0] = name;
 		if (contains(opts, "scale")) {
-			vector<string>::const_iterator it = allopts.begin();
+			vector<string>::iterator it = allopts.begin();
 			for (; it != allopts.end() ; ++it) {
 				string const opt = *it;
 				if (prefixIs(opt, "scaled=") || prefixIs(opt, "scale=")) {
@@ -1383,7 +1383,7 @@ void Preamble::handle_package(Parser &p, string const & name,
 	if (is_known(name, known_typewriter_font_packages)) {
 		h_font_typewriter[0] = name;
 		if (contains(opts, "scale")) {
-			vector<string>::const_iterator it = allopts.begin();
+			vector<string>::iterator it = allopts.begin();
 			for (; it != allopts.end() ; ++it) {
 				string const opt = *it;
 				if (prefixIs(opt, "scaled=") || prefixIs(opt, "scale=")) {