[NetworkManager-openvpn] service: add logic to detect OpenVPN <=2.4

[Lubomir Rintel <lkundrak src gnome org>]

commit 1d47d12fac2930775a93508cb1e037dd7870b70b
Author: Ernestas Kulik <ernestas@baltic.engineering>
Date:   Sun Aug 28 10:44:56 2022 +0300

    service: add logic to detect OpenVPN <=2.4
    
    Things like allow-compression are only supported it 2.4+, but there is
    currently no way to detect it.
    
    https://gitlab.gnome.org/GNOME/NetworkManager-openvpn/-/merge_requests/54

 src/nm-openvpn-service.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/src/nm-openvpn-service.c b/src/nm-openvpn-service.c
index 3731e89..cb9d01d 100644
--- a/src/nm-openvpn-service.c
+++ b/src/nm-openvpn-service.c
@@ -89,6 +89,7 @@ typedef enum {
        OPENVPN_BINARY_VERSION_INVALID,
        OPENVPN_BINARY_VERSION_UNKNOWN,
        OPENVPN_BINARY_VERSION_2_3_OR_OLDER,
+       OPENVPN_BINARY_VERSION_2_4_OR_OLDER,
        OPENVPN_BINARY_VERSION_2_4_OR_NEWER,
 } OpenvpnBinaryVersion;
 
@@ -576,6 +577,9 @@ openvpn_binary_detect_version (const char *exepath)
 
        if (n <= 3)
                return OPENVPN_BINARY_VERSION_2_3_OR_OLDER;
+       if (n <= 4)
+               return OPENVPN_BINARY_VERSION_2_4_OR_OLDER;
+
        return OPENVPN_BINARY_VERSION_2_4_OR_NEWER;
 }