[libgda] Avoid an implicit fallthrough warning with gcc 7.

[Murray Cumming <murrayc src gnome org>]

commit 849d9d7ecbfd15aac1256ee623983991d6cbd694
Author: Murray Cumming <murrayc murrayc com>
Date:   Sun Oct 29 21:07:32 2017 +0100

    Avoid an implicit fallthrough warning with gcc 7.
    
    See
    https://developers.redhat.com/blog/2017/03/10/wimplicit-fallthrough-in-gcc-7/
    
    This was the warning:
    
    libcsv.c: In function ‘csv_fini’:
    libcsv.c:162:20: error: this statement may fall through [-Werror=implicit-fallthrough=]
           p->entry_pos -= p->spaces + 1;  /* get rid of spaces and original quote */
           ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~
    libcsv.c:163:5: note: here
         case FIELD_NOT_BEGUN:
         ^~~~

 libgda/libcsv.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/libgda/libcsv.c b/libgda/libcsv.c
index 95795f0..99b19ef 100644
--- a/libgda/libcsv.c
+++ b/libgda/libcsv.c
@@ -160,6 +160,7 @@ csv_fini(struct csv_parser *p, void (*cb1)(char *, size_t, void *), void (*cb2)(
   switch (p->pstate) {
     case FIELD_MIGHT_HAVE_ENDED:
       p->entry_pos -= p->spaces + 1;  /* get rid of spaces and original quote */
+      /* fallthrough */
     case FIELD_NOT_BEGUN:
     case FIELD_BEGUN:
       quoted = p->quoted, pstate = p->pstate;