Temporarily switch to boost::regex

In combination with musl, parser crashed. glibc fine. Could not pinpoint
down the exact reason mainly due to time constraints. Strange, in both
cases actually libstdc++ is used, so this is very odd.

parser.cpp

@@ -27,7 +27,6 @@ SOFTWARE.
 #include "parser.h"
 #include "utils.h"
 #include "htmllink.h"
-
 std::vector<Headline> Parser::extractHeadlines(std::string content) const
 {
 	std::vector<Headline> result;
@@ -82,7 +81,7 @@ std::string Parser::extractCommand(std::string cmdname, std::string content) con
 	}
 	return "";
 }
-std::string Parser::processLink(const PageDao &pageDao, UrlProvider &urlProvider, std::smatch &match) const
+std::string Parser::processLink(const PageDao &pageDao, UrlProvider &urlProvider, boost::smatch &match) const
 {
 	std::string linktag = match.str(1);
 	std::string inside = match.str(2);
@@ -121,8 +120,8 @@ std::string Parser::parse(const PageDao &pagedao, UrlProvider &provider, std::st
 {
 	std::string result;
 	// we don't care about commands, but we nevertheless replace them with empty strings
-	std::regex tagfinder(R"(\[(b|i|u|li||ul|ol|link|wikilink|h\d|cmd:rename|cmd:redirect)*?\]((\s|\S)*?)\[/\1])");
-	result = utils::regex_callback_replacer(tagfinder, content, [&](std::smatch &match) {
+	boost::regex tagfinder(R"(\[(b|i|u|li||ul|ol|link|wikilink|h\d|cmd:rename|cmd:redirect)*?\]((\s|\S)*?)\[/\1])");
+	result = utils::regex_callback_replacer(tagfinder, content, [&](boost::smatch &match) {
 		std::string tag = match.str(1);
 		std::string content = match.str(2);
 		std::string justreplace[] = {"b", "i", "u", "ul", "li", "ol"};