utils: add locale_workaround

Attempt to work around some locale handling throwing in some systems.

   "locale::facet::_S_create_c_locale name not valid"

Ugly, but maybe it helps.

lib/utils/mu-utils.cc

@@ -19,6 +19,7 @@
 
 #ifndef _XOPEN_SOURCE
 #define _XOPEN_SOURCE
+#include <stdexcept>
 #endif /*_XOPEN_SOURCE*/
 
 #include <array>
@@ -606,3 +607,21 @@ Mu::TempDir::~TempDir()
 
 	g_debug("removed '%s'", path_.c_str());
 }
+
+bool
+Mu::locale_workaround()
+{
+	// quite horrible... but some systems break otherwise with
+	//  https://github.com/djcb/mu/issues/2252
+
+	for (auto&& loc : {"", "en_US.UTF-8", "C" }) {
+		try {
+			std::locale::global(std::locale(loc));
+			return true;
+		} catch (const std::runtime_error& re) {
+			continue;
+		}
+	}
+
+	return false;
+}