Kernel: Fix -Wunreachable-code warnings from clang

Kernel/CommandLine.cpp

@@ -46,7 +46,7 @@ UNMAP_AFTER_INIT void CommandLine::build_commandline(const String& cmdline_from_
 {
     StringBuilder builder;
     builder.append(cmdline_from_bootloader);
-    if (!s_embedded_cmd_line.is_empty()) {
+    if constexpr (!s_embedded_cmd_line.is_empty()) {
         builder.append(" ");
         builder.append(s_embedded_cmd_line);
     }

Kernel/KSyms.cpp

@@ -111,10 +111,8 @@ NEVER_INLINE static void dump_backtrace_impl(FlatPtr base_pointer, bool use_ksym
     } while (0)
 
     SmapDisabler disabler;
-    if (use_ksyms && !g_kernel_symbols_available) {
+    if (use_ksyms && !g_kernel_symbols_available)
         Processor::halt();
-        return;
-    }
 
     struct RecognizedSymbol {
         FlatPtr address;

Kernel/Net/LocalSocket.cpp

@@ -413,7 +413,7 @@ KResult LocalSocket::getsockopt(OpenFileDescription& description, int level, int
         default:
             return EINVAL;
         }
-        break;
+        VERIFY_NOT_REACHED();
     }
     default:
         return Socket::getsockopt(description, level, option, value, value_size);

Kernel/Net/NetworkTask.cpp

@@ -531,8 +531,8 @@ void handle_tcp(IPv4Packet const& ipv4_packet, Time const& packet_timestamp)
                 socket->set_state(TCPSocket::State::Closed);
                 return;
             }
+            VERIFY_NOT_REACHED();
 
-            return;
         case TCPFlags::SYN:
             dbgln("handle_tcp: ignoring SYN for partially established connection");
             return;

Kernel/Process.cpp

@@ -592,8 +592,8 @@ bool Process::dump_perfcore()
     }
     auto json_buffer = UserOrKernelBuffer::for_kernel_buffer(json->data());
     if (description.write(json_buffer, json->size()).is_error()) {
-        return false;
         dbgln("Failed to generate perfcore for pid {}: Could not write to perfcore file.", pid().value());
+        return false;
     }
 
     dbgln("Wrote perfcore for pid {} to {}", pid().value(), description.absolute_path());

Kernel/Syscall.cpp

@@ -141,10 +141,8 @@ KResultOr<FlatPtr> handle(RegisterState& regs, FlatPtr function, FlatPtr arg1, F
         switch (function) {
         case SC_exit:
             process.sys$exit(arg1);
-            break;
         case SC_exit_thread:
             process.sys$exit_thread(arg1, arg2, arg3);
-            break;
         default:
             VERIFY_NOT_REACHED();
         }

Kernel/Syscalls/prctl.cpp

@@ -18,10 +18,8 @@ KResultOr<FlatPtr> Process::sys$prctl(int option, FlatPtr arg1, [[maybe_unused]]
     case PR_SET_DUMPABLE:
         set_dumpable(arg1);
         return 0;
-    default:
-        return EINVAL;
     }
-    return 0;
+    return EINVAL;
 }
 
 }