[gegl] configure.ac: verify zlib version

[Ell <ell src gnome org>]

commit d0fa5a974cda4d4a69ff37eaec3ed3901c10abe3
Author: Ell <ell_se yahoo com>
Date:   Mon Dec 17 07:23:08 2018 -0500

    configure.ac: verify zlib version
    
    ... and whitespace foo in gegl-compression-zlib.c

 configure.ac                        | 2 +-
 gegl/buffer/gegl-compression-zlib.c | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/configure.ac b/configure.ac
index 8afb391a5..8a56a81c2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -833,7 +833,7 @@ AC_ARG_WITH(zlib, [  --without-zlib          build without zlib support])
 
 have_zlib="no"
 if test "x$with_zlib" != "xno"; then
-  PKG_CHECK_MODULES(ZLIB, zlib,
+  PKG_CHECK_MODULES(ZLIB, zlib >= zlib_required_version,
     AC_DEFINE(HAVE_ZLIB, 1,
                 [Define to 1 if the zlib library is available])
     have_zlib="yes",
diff --git a/gegl/buffer/gegl-compression-zlib.c b/gegl/buffer/gegl-compression-zlib.c
index f24d29a92..cdaf39d6c 100644
--- a/gegl/buffer/gegl-compression-zlib.c
+++ b/gegl/buffer/gegl-compression-zlib.c
@@ -25,6 +25,7 @@
 
 #include <zlib.h>
 
+
 typedef struct
 {
   GeglCompression compression;