Kill multi-byte comments in fxet_list.h

No functional changes, just tidying some stray characters,
plus kill trailing whitespace while we're at it.

TBR=thestig@chromium.org
BUG=https://code.google.com/p/pdfium/issues/detail?id=123

Review URL: https://codereview.chromium.org/953143002
1 file changed