[vte] build: Fix option name

[Christian Persch <chpe src gnome org>]

commit cb947de6621ffbfb32971968f3dbcd6b1e511073
Author: Christian Persch <chpe gnome org>
Date:   Sun Feb 5 21:01:27 2017 +0100

    build: Fix option name
    
    The one-dash version works too, but two-dash is correct.

 doc/reference/Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/doc/reference/Makefile.am b/doc/reference/Makefile.am
index 59f804c..df35710 100644
--- a/doc/reference/Makefile.am
+++ b/doc/reference/Makefile.am
@@ -37,7 +37,7 @@ SCAN_OPTIONS = --deprecated-guards="VTE_DISABLE_DEPRECATED" --ignore-decorators=
 
 # Extra options to supply to gtkdoc-mkdb.
 # e.g. MKDB_OPTIONS=--sgml-mode --output-format=xml
-MKDB_OPTIONS = -source-suffixes=h,hh,c,cc --xml-mode --output-format=xml --name-space=vte
+MKDB_OPTIONS = --source-suffixes=h,hh,c,cc --xml-mode --output-format=xml --name-space=vte
 
 # Extra options to supply to gtkdoc-mktmpl
 # e.g. MKTMPL_OPTIONS=--only-section-tmpl