use std chr functions

The ones in std have overloads for const char/char.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/db/update/Archive.cxx

@@ -55,7 +55,7 @@ void
 UpdateWalk::UpdateArchiveTree(ArchiveFile &archive, Directory &directory,
 			      const char *name) noexcept
 {
-	const char *tmp = strchr(name, '/');
+	const char *tmp = std::strchr(name, '/');
 	if (tmp) {
 		const std::string_view child_name(name, tmp - name);
 		//add dir is not there already