LibWeb: Add Solaris/SunOS platform string to ResourceLoader

Author: https://github.com/ghost
Commit: 1dbc9bcc0b
Pull-request: https://github.com/SerenityOS/serenity/pull/17623
Reviewed-by: https://github.com/ADKaster ✅
Reviewed-by: https://github.com/elcuco
Reviewed-by: https://github.com/kleinesfilmroellchen ✅
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibWeb/Loader/ResourceLoader.h

@@ -40,6 +40,8 @@ namespace Web {
 #    define OS_STRING "NetBSD"
 #elif defined(AK_OS_DRAGONFLY)
 #    define OS_STRING "DragonFly"
+#elif defined(AK_OS_SOLARIS)
+#    define OS_STRING "SunOS"
 #else
 #    error Unknown OS
 #endif