core: Include cstring whenever strncpy is used (#7267)

Fixes ppc64le build in alpine

hyprctl/main.cpp

@@ -26,6 +26,7 @@
 #include <regex>
 #include <sys/socket.h>
 #include <hyprutils/string/String.hpp>
+#include <cstring>
 using namespace Hyprutils::String;
 
 #include "Strings.hpp"

src/helpers/SdDaemon.cpp

@@ -8,6 +8,7 @@
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <string.h>
+#include <cstring>
 
 namespace Systemd {
     int SdBooted(void) {

src/managers/EventManager.cpp

@@ -8,6 +8,7 @@
 #include <sys/types.h>
 #include <sys/un.h>
 #include <unistd.h>
+#include <cstring>
 
 CEventManager::CEventManager() {
     m_iSocketFD = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);

src/xwayland/Server.cpp

@@ -19,6 +19,7 @@
 #include <sys/un.h>
 #include <unistd.h>
 #include <filesystem>
+#include <cstring>
 
 // TODO: cleanup
 static bool set_cloexec(int fd, bool cloexec) {