Remove File::eOpenOptionAppend from the mode used by 'platform file
open' command. According to POSIX, O_APPEND causes all successive
writes to be done at the end of the file. This effectively makes
the offset argument to 'platform file write' meaningless.
Furthermore, apparently O_APPEND is not implemented reliably everywhere.
The Linux manpage for pwrite(2) suggests that Linux does respect
O_APPEND there while according to POSIX it should not, so the actual
behavior would be dependent on how the vFile:pwrite packet is
implemented on the server.
Ideally, the mode used for opening flags would be provided via options.
However, changing the default mode seems to be a reasonable intermediate
solution.
Differential Revision: https://reviews.llvm.org/D107664
2c6d90d741