csource: Fix sed(1) invocation
csource: Fix sed(1) invocation

There is no need to specify '-' as the filename for sed(1):
- The default behavior is to read stdin
- It was not done in all places
- It breaks on NetBSD sed(1) (although I am tempted to fix it now :-)
  and it does not work

google/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller,google/syzkaller,xairy/syzkaller