[boost] [RC1_34_0]Request to add Intel C 9.1 + VC8 to the supported compilers list

Intel C++ 9.1 + VC8 now has less regression errors than IC9.1 + VC7.1 and I expect those remaining issues will go away when VC8 errors are either fixed or marked. It makes sense to mark it as officially supported. The Windows x64 test results also look very promising but I can understand we do not want to further delay 1.34. Thanks, Sean