[Minor] Enable missing_noreturn compiler warning

cmake/CompilerWarnings.cmake

@@ -10,6 +10,7 @@ CHECK_C_COMPILER_FLAG(-Wno-sign-compare SUPPORT_WSIGN_COMPARE)
 CHECK_C_COMPILER_FLAG(-Wstrict-prototypes SUPPORT_WSTRICT_PROTOTYPES)
 CHECK_C_COMPILER_FLAG(-pedantic SUPPORT_PEDANTIC_FLAG)
 CHECK_C_COMPILER_FLAG(-Wno-unused-const-variable SUPPORT_WNO_UNUSED_CONST)
+CHECK_C_COMPILER_FLAG(-Wmissing-noreturn SUPPORT_WMISSING_NORETURN)
 # GCC 6 specific
 CHECK_C_COMPILER_FLAG(-Wnull-dereference SUPPORT_WNULL_DEREFERENCE)
 CHECK_C_COMPILER_FLAG(-Wduplicated-cond SUPPORT_WDUPLICATED_COND)
@@ -67,6 +68,9 @@ ENDIF()
 IF(SUPPORT_WIMPLICIT_FALLTHROUGH)
     ADD_COMPILE_OPTIONS("-Wno-implicit-fallthrough")
 ENDIF(SUPPORT_WIMPLICIT_FALLTHROUGH)
+IF(SUPPORT_WMISSING_NORETURN)
+    ADD_COMPILE_OPTIONS("-Wmissing-noreturn")
+ENDIF(SUPPORT_WMISSING_NORETURN)
 
 CHECK_C_COMPILER_FLAG(-fPIC SUPPORT_FPIC)
 IF(SUPPORT_FPIC)

contrib/snowball/compiler/driver.c

@@ -25,6 +25,7 @@ static int eq(const char * s1, const char * s2) {
     return strcmp(s1, s2) == 0;
 }
 
+__attribute__((noreturn))
 static void print_arglist(int exit_code) {
     FILE * f = exit_code ? stderr : stdout;
     fprintf(f, "Usage: snowball SOURCE_FILE... [OPTIONS]\n\n"

src/controller.c

@@ -3477,6 +3477,7 @@ rspamd_controller_register_plugins_paths (struct rspamd_controller_worker_ctx *c
 /*
  * Start worker process
  */
+__attribute__((noreturn))
 void
 start_controller_worker (struct rspamd_worker *worker)
 {

src/fuzzy_storage.c

@@ -2120,6 +2120,7 @@ fuzzy_peer_rep (struct rspamd_worker *worker,
 /*
  * Start worker process
  */
+__attribute__((noreturn))
 void
 start_fuzzy (struct rspamd_worker *worker)
 {

src/libcryptobox/cryptobox.c

@@ -93,6 +93,7 @@ rspamd_cryptobox_cpuid (gint cpu[4], gint info)
 static sig_atomic_t ok = 0;
 static jmp_buf j;
 
+__attribute__((noreturn))
 static void
 rspamd_cryptobox_ill_handler (int signo)
 {

src/rspamadm/configdump.c

@@ -230,6 +230,7 @@ rspamadm_dump_section_obj (struct rspamd_config *cfg,
 	}
 }
 
+__attribute__((noreturn))
 static void
 rspamadm_configdump (gint argc, gchar **argv, const struct rspamadm_command *cmd)
 {

src/rspamadm/confighelp.c

@@ -190,6 +190,7 @@ rspamadm_confighelp_search_word (const ucl_object_t *obj, const gchar *str)
 	return res;
 }
 
+__attribute__((noreturn))
 static void
 rspamadm_confighelp (gint argc, gchar **argv, const struct rspamadm_command *cmd)
 {

src/rspamd_proxy.c

@@ -2282,6 +2282,7 @@ adjust_upstreams_limits (struct rspamd_proxy_ctx *ctx)
 	}
 }
 
+__attribute__((noreturn))
 void
 start_rspamd_proxy (struct rspamd_worker *worker)
 {

src/worker.c

@@ -477,6 +477,7 @@ init_worker (struct rspamd_config *cfg)
 /*
  * Start worker process
  */
+__attribute__((noreturn))
 void
 start_worker (struct rspamd_worker *worker)
 {