Ignore sys_config.h.in built by bootstrap.
Ignore sys_config.h.in built by bootstrap.

During the execution of ./bootstrap the file sys_config.h.in is
created, which causes it to be displayed when git status is used.

Bitblade-org/mgsim,Bitblade-org/mgsim,Bitblade-org/mgsim,Bitblade-org/mgsim