Fix some issues reported by Coverity (#1150)

module_wasm_app.c: add return value check for wasm_runtime_call_wasm
aot_runtime.c: add return value check for aot_get_default_memory
aot_runtime.c: add return value check before calling wasm app malloc/free func
wasm_runtime_common.c: fix dead code warning in wasm_runtime_load_from_sections
aot_emit_memory.c: fix potential integer overflow issue
wasm_runtime.c: remove dead code in memory_instantiate, add assertion for globals
samples simple/gui/littlevgl: fix fields of struct sigaction initialization issue
host-tool: add return value check for sendto

samples/gui/wasm-runtime-wgl/src/platform/linux/iwasm_main.c

@@ -175,9 +175,11 @@ func_server_mode(void *arg)
     struct sockaddr_in serv_addr, cli_addr;
     int n;
     char buff[MAX];
-
     struct sigaction sa;
+
     sa.sa_handler = SIG_IGN;
+    sa.sa_flags = 0;
+    sigemptyset(&sa.sa_mask);
     sigaction(SIGPIPE, &sa, 0);
 
     /* First call to socket() function */