misc: Address compiler warning about deprecated header

In file included from osmo_client_main.c:27:0:
/home/ich/install/openbsc/include/osmocom/core/process.h:1:2: warning: #warning "Update from osmocom/core/process.h to osmocom/core/application.h" [-Wcpp]
 #warning "Update from osmocom/core/process.h to osmocom/core/application.h"

Change-Id: Id60cf90ebb7255d79f8e3bdb81f099f1362d538b
diff --git a/src/osmo_client_main.c b/src/osmo_client_main.c
index 9ea0b66..a38cc80 100644
--- a/src/osmo_client_main.c
+++ b/src/osmo_client_main.c
@@ -24,7 +24,6 @@
 #include <osmo-pcap/osmo_pcap_client.h>
 
 #include <osmocom/core/application.h>
-#include <osmocom/core/process.h>
 #include <osmocom/core/rate_ctr.h>
 #include <osmocom/core/select.h>
 #include <osmocom/core/talloc.h>