Set TLS_DEFAULT_CA_FILE for Debian

--- a/tls_internal.h
+++ b/tls_internal.h
@@ -29,7 +29,7 @@
 __BEGIN_HIDDEN_DECLS
 
 #ifndef TLS_DEFAULT_CA_FILE
-#define TLS_DEFAULT_CA_FILE	"/etc/ssl/cert.pem"
+#define TLS_DEFAULT_CA_FILE	"/etc/ssl/certs/ca-certificates.crt"
 #endif
 
 #define TLS_CIPHERS_DEFAULT	TLS_CIPHERS_COMPAT
