MEDIUM: init: convert all trivial registration calls to initcalls

This switches explicit calls to various trivial registration methods for
keywords, muxes or protocols from constructors to INITCALL1 at stage
STG_REGISTER. All these calls have in common to consume a single pointer
and return void. Doing this removes 26 constructors. The following calls
were addressed :

- acl_register_keywords
- bind_register_keywords
- cfg_register_keywords
- cli_register_kw
- flt_register_keywords
- http_req_keywords_register
- http_res_keywords_register
- protocol_register
- register_mux_proto
- sample_register_convs
- sample_register_fetches
- srv_register_keywords
- tcp_req_conn_keywords_register
- tcp_req_cont_keywords_register
- tcp_req_sess_keywords_register
- tcp_res_cont_keywords_register
- flt_register_keywords
diff --git a/src/da.c b/src/da.c
index 990267a..c1c07e3 100644
--- a/src/da.c
+++ b/src/da.c
@@ -3,6 +3,7 @@
 #include <common/cfgparse.h>
 #include <common/errors.h>
 #include <common/http.h>
+#include <common/initcall.h>
 #include <proto/arg.h>
 #include <proto/http_fetch.h>
 #include <proto/log.h>
@@ -376,25 +377,28 @@
 	{ 0, NULL, NULL },
 }};
 
+INITCALL1(STG_REGISTER, cfg_register_keywords, &dacfg_kws);
+
 /* Note: must not be declared <const> as its list will be overwritten */
 static struct sample_fetch_kw_list fetch_kws = {ILH, {
 	{ "da-csv-fetch", da_haproxy_fetch, ARG12(1,STR,STR,STR,STR,STR,STR,STR,STR,STR,STR,STR,STR), NULL, SMP_T_STR, SMP_USE_HRQHV },
 	{ NULL, NULL, 0, 0, 0 },
 }};
 
+INITCALL1(STG_REGISTER, sample_register_fetches, &fetch_kws);
+
 /* Note: must not be declared <const> as its list will be overwritten */
 static struct sample_conv_kw_list conv_kws = {ILH, {
 	{ "da-csv-conv", da_haproxy_conv, ARG12(1,STR,STR,STR,STR,STR,STR,STR,STR,STR,STR,STR,STR), NULL, SMP_T_STR, SMP_T_STR },
 	{ NULL, NULL, 0, 0, 0 },
 }};
 
+INITCALL1(STG_REGISTER, sample_register_convs, &conv_kws);
+
 __attribute__((constructor))
 static void __da_init(void)
 {
 	/* register sample fetch and format conversion keywords */
-	sample_register_fetches(&fetch_kws);
-	sample_register_convs(&conv_kws);
-	cfg_register_keywords(&dacfg_kws);
 	hap_register_build_opts("Built with DeviceAtlas support.", 0);
 	hap_register_post_check(init_deviceatlas);
 	hap_register_post_deinit(deinit_deviceatlas);