Make esme struct shared

This helps to merge similar code from smpp_mirror and smpp_* in follow-up patches.

Related: OS#5568
Change-Id: I8f7ac2c00d16660925dd0b03aa1a0973edf9eb70
diff --git a/include/osmocom/msc/gsm_data.h b/include/osmocom/msc/gsm_data.h
index 78b9c9a..43944e7 100644
--- a/include/osmocom/msc/gsm_data.h
+++ b/include/osmocom/msc/gsm_data.h
@@ -268,7 +268,7 @@
 	struct sms_queue_config *sms_queue_cfg;
 };
 
-struct osmo_esme;
+struct smpp_esme;
 
 enum gsm_sms_source_id {
 	SMS_SOURCE_UNKNOWN = 0,
@@ -297,7 +297,7 @@
 	} gsm411;
 
 	struct {
-		struct osmo_esme *esme;
+		struct smpp_esme *esme;
 		uint32_t sequence_nr;
 		int transaction_mode;
 		char msg_id[16];