[gegl] build: further tidy up exiv2 test

[Øyvind Kolås <ok src gnome org>]

commit fe8e1aa5fa067de5ce5f47882c0033e4825f3712
Author: Øyvind Kolås <pippin gimp org>
Date:   Sun Jul 23 00:32:50 2017 +0200

    build: further tidy up exiv2 test

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index ed7c54b..b7547fc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1120,7 +1120,7 @@ AC_SUBST(LIBSPIRO)
 
 AC_ARG_WITH(exiv2, [  --without-exiv2         build without libexiv2 support])
 
-have_libexiv2="no"
+have_exiv2="no"
 if test "x$with_exiv2" != "xno"; then
   PKG_CHECK_MODULES(EXIV2, exiv2,
     have_exiv2="yes",