Makefile parsing inconsitency with comments

If a comment is interleaved with the values of a macro defintion, makefile parser doesn't ignore its contents.
This behavior conflicts with IDE-writers, since it attempts to treat the comment as a valid entry and fails on it.

For instance:
```makefile

SOURCES = \
  file_x.c\
  # file_y.c\   <--this comment will be treated by parser as a file, and it shouldn't
  file_z.c

```
