gcc 特性支持不完整

[yetist]

编译 gcc 时发现不支持以下特性：

configure:3294: checking for libitm support                                      
configure:3300: result: no                                                       
configure:3313: checking for libsanitizer support                                
configure:3319: result: no                                                       
configure:3332: checking for libvtv support                                      
configure:3338: result: no                                                       
configure:3462: checking for libphobos support                                   
configure:3468: result: no                                                       

请确认这些特性，哪些是可以在 LoongArch 上支持的，请增加相关支持，谢谢。