[PATCH] Don't output #line 0 directives for prototypes.

It is not valid for the integer argument of a #line directive to be 0.
However, the generated C source will contain such a directive around the
prototypes of private functions that do not appear in the .gob file.
For example, the trivial

  class My:Test from G:Object {
  }

generates the invalid C code:

  #line 0 "my-test.gob"
  static void my_test_init (MyTest * o) G_GNUC_UNUSED;
  /* ... */
  #line 0 "my-test.gob"
  static void my_test_class_init (MyTestClass * c) G_GNUC_UNUSED;

Fix this up and add an assertion to out_addline_infile to catch future
problems of this nature.
---

Hopefully this is the right place to send patches!  The gob2 website
doesn't make any mention of where they should be sent.

 src/main.c |    6 ++++--
 src/out.c  |    2 ++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/main.c b/src/main.c
index 5d2d4c9..cd8edef 100644
--- a/src/main.c