Support g++-4.6 in configuration script.
Support g++-4.6 in configuration script.

gcc 4.6 doesn't have the -std=c++11 option, it uses the not-yet-finalized
-std=c++0x option.  Use whichever is found to be appropriate at configure
time.

php/pecl-languages-v8js,phpv8/v8js,ABaldwinHunter/v8js-clone,ABaldwinHunter/v8js-clone,stesie/v8js,rosmo/v8js,zzhh9857/v8js,uniconstructor/v8js,stesie/v8js,phpv8/v8js,rosmo/v8js,php/pecl-languages-v8js,php/pecl-languages-v8js,zzhh9857/v8js,zzhh9857/v8js,ABaldwinHunter/v8js-clone,stesie/v8js,dayed/v8js,dayed/v8js,preillyme/v8js,preillyme/v8js,preillyme/v8js,preillyme/v8js,zzhh9857/v8js,uniconstructor/v8js,uniconstructor/v8js,rosmo/v8js,php/pecl-languages-v8js,stesie/v8js,uniconstructor/v8js,phpv8/v8js,dayed/v8js,dayed/v8js,rosmo/v8js,ABaldwinHunter/v8js-clone