### Description

We are having several customers with crashes during calls to RPC `permissions.trustedReload` even after introducing the basic safety for concurrent RPC reload https://github.com/kamailio/kamailio/commit/c87f5202d778cf110ce0fbbc554310c1...

### Possible solution

It seems that we need to implement locking in order to be sure the memory is not gone in the middle of a read.

#### Reproduction

It's quite difficult to reproduce since `match_hash_table` call has to happen during a RPC reload

#### Debugging Data

``` (gdb) bt full #0 match_hash_table (table=<optimized out>, msg=msg@entry=0x7fc3d800a808, src_ip_c_str=src_ip_c_str@entry=0x7fc3d7f217b8 "A.A.A.A", proto=proto@entry=1, from_uri=from_uri@entry=0x7fc3d7f1b750 "sip:fake@B.B.B.B") at hash.c:280 __func__ = "match_hash_table" ruri = <optimized out> ruri_string = "sip:41584006001@B.B.B.B:5060\000\264{\224\377\177\000\000\000\240\200\331\302\177\000\000\300\000\000\000\000\000\000\000\332\003\000\000\000\000\000\000\300\067~\372PV\000\000\000\220 \324m,\233߁\260\341D\334\302\177\000\000\260go\372PV\000\000P\343!\332\302\177\000\000\004\340{\372PV\000\000`;~\372PV\000\000\300\067~\372PV\000\000@\024\000\000\000\000\000\000`\342!\332\302\177\000\000\001\00 0\000\000\000\000\000\000\310\066\204\331\302\177\000\000\000\240\200\331\302\177\000\000\300\000\000\000\000\000\000\000\300\067~\372PV\000\000`;~\372PV\000\000\332\003\000\000\000\000\000\000\000"... preg = {__buffer = 0x0, __allocated = 0, __used = 224, __syntax = 16843462, __fastmap = 0x0, __translate = 0x0, re_nsub = 0, __can_be_null = 0, __regs_allocated = 0, __fastmap_accurate = 1, __no_sub = 1, __not_bol = 0, __not_eol = 0, __newline_anchor = 0} np = 0x455449564e492035 src_ip = {s = 0x7fc3d7f217b8 "A.A.A.A", len = <optimized out>} val = <optimized out> count = 0 #1 0x00007fc3d2362765 in allow_trusted (msg=msg@entry=0x7fc3d800a808, src_ip=0x7fc3d7f217b8 "A.A.A.A", proto=proto@entry=1, from_uri=from_uri@entry=0x7fc3d7f1b750 "sip:fake@B.B.B.B") at trusted.c:499 __func__ = "allow_trusted" result = <optimized out> res = 0x0 keys = {0x7fc3d7f1b750} vals = {{type = 3595139888, nul = 32707, free = -671045624, val = {int_val = -1803829520, ll_val = 140735684525808, double_val = 6.9532666868153257e-310, time_val = 140735684525808, string_val = 0x7fff947bbef0 "\001", str_val = {s = 0x7fff947bbef0 "\001", len = -94468017}, blob_val = {s = 0x7fff947bbef0 "\001", len = -94468017}, bitmap_val = 2491137776, uint_val = 2491137776, ull_val = 140735684525808}}} cols = {0x0, 0x5650fa650c25 <pv_printf+229>, 0x7fff947bb670, 0x0} #2 0x00007fc3d2363ef3 in allow_trusted_furi (_msg=_msg@entry=0x7fc3d800a808, _src_ip_sp=_src_ip_sp@entry=0x7fc3d6494340 "xEI\326\303\177", _proto_sp=_proto_sp@entry=0x7fc3d64925e0 "\330\375H\326\303\177", from_uri=0x7fc3d7f1b750 "sip:fake@B.B.B.B") at trusted.c:590 src_ip = {s = 0x7fc3d7f217b8 "A.A.A.A", len = 11} proto = {s = 0x7fc3d7f27820 "udp", len = 3} proto_int = 1 __func__ = "allow_trusted_furi" #3 0x00007fc3d23647d0 in allow_trusted_3 (_msg=0x7fc3d800a808, _src_ip_sp=0x7fc3d6494340 "xEI\326\303\177", _proto_sp=0x7fc3d64925e0 "\330\375H\326\303\177", _from_uri=<optimized out>) at trusted.c:634 from_uri = {s = 0x7fc3d7f1b750 "sip:fake@B.B.B.B", len = 34} __func__ = "allow_trusted_3" #4 0x00005650fa513319 in do_action (h=h@entry=0x7fff947bbef0, a=a@entry=0x7fc3d6497b30, msg=msg@entry=0x7fc3d800a808) at core/action.c:1085 ```