#1550 CMake: empty comment continuation issue

[Colomban Wendling]

CMake lexer wrongly continues comment on the next line if the comment is completely empty:

# this works OK
this is not a comment
#
but this is highlighted as one

Originally reported against Geany: [geany:bugs:#1005]

[Colomban Wendling]

Proposed patch

[Neil Hodgson]

Committed as [fee747].