Used for merge

*Delete the script codes.
*Modify the copy right
*Add --enable-winrtapi to configure
*Modify the doc/platform.texi
*change restrict to av_restrict, this should be a bug in compiling.
The `test` there is to prevent `gas-preprocessor.pl` from being included twice, make `${gas}` equal `gas-preprocessor.plgas-preprocessor.pl`.