[gimp] configure: libwebp(de)?mux follow libwebp version.

[Jehan Pagès <jehanp src gnome org>]

commit b6c49058448427bfdfd211bcbc4221e09aec0251
Author: Jehan <jehan girinstud io>
Date:   Tue Aug 1 19:19:18 2017 +0200

    configure: libwebp(de)?mux follow libwebp version.
    
    They are sub-libraries of libwebp, enabled by build options
    (--enable-libwebp(de)?mux), and therefore I don't think it makes sense
    to have separate version prerequisites.
    
    Also let's improve the config output by testing for libwebp(de)?mux only
    when libwebp check is successful and displaying more accurate info
    (instead of saying "WebP not found", "WebP not built with libwebpmux" is
    much more accurate for instance, in order to understand the problem if
    you are sure you installed the proper version of libwebp).

 configure.ac |   22 +++++++++-------------
 1 files changed, 9 insertions(+), 13 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index dab4953..dcbdded 100644
--- a/configure.ac
+++ b/configure.ac
@@ -77,8 +77,6 @@ m4_define([gtk_mac_integration_required_version], [2.0.0])
 m4_define([intltool_required_version], [0.40.1])
 m4_define([python2_required_version], [2.5.0])
 m4_define([webp_required_version], [0.6.0])
-m4_define([webpmux_required_version], [0.5.1])
-m4_define([webpdemux_required_version], [0.5.1])
 
 # Current test considers only 2 version numbers. If we update the recommended
 # version of gettext with more version numbers, please update the tests.
@@ -164,8 +162,6 @@ OPENEXR_REQUIRED_VERSION=openexr_required_version
 INTLTOOL_REQUIRED_VERSION=intltool_required_version
 PYTHON2_REQUIRED_VERSION=python2_required_version
 WEBP_REQUIRED_VERSION=webp_required_version
-WEBPMUX_REQUIRED_VERSION=webpmux_required_version
-WEBPDEMUX_REQUIRED_VERSION=webpdemux_required_version
 XGETTEXT_RECOMMENDED_VERSION=xgettext_recommended_version
 AC_SUBST(GLIB_REQUIRED_VERSION)
 AC_SUBST(GDK_PIXBUF_REQUIRED_VERSION)
@@ -195,8 +191,6 @@ AC_SUBST(OPENEXR_REQUIRED_VERSION)
 AC_SUBST(INTLTOOL_REQUIRED_VERSION)
 AC_SUBST(PYTHON2_REQUIRED_VERSION)
 AC_SUBST(WEBP_REQUIRED_VERSION)
-AC_SUBST(WEBPMUX_REQUIRED_VERSION)
-AC_SUBST(WEBPDEMUX_REQUIRED_VERSION)
 AC_SUBST(XGETTEXT_RECOMMENDED_VERSION)
 
 # The symbol GIMP_UNSTABLE is defined above for substitution in
@@ -1623,13 +1617,15 @@ AC_ARG_WITH(webp, [  --without-webp       build without WebP support])
 have_webp=no
 if test "x$with_webp" != xno; then
   have_webp=yes
-  PKG_CHECK_MODULES(WEBP, libwebp >= webp_required_version,,
-    [have_webp="no (WebP not found)"])
-
-  PKG_CHECK_MODULES(WEBPMUX, libwebpmux >= webpmux_required_version,,
-    [have_webp="no (WebP not found)"])
-
-  PKG_CHECK_MODULES(WEBPDEMUX, libwebpdemux >= webpdemux_required_version,,
+  PKG_CHECK_MODULES(WEBP, libwebp >= webp_required_version,
+    [
+      PKG_CHECK_MODULES(WEBPMUX, libwebpmux >= webp_required_version,
+        [
+          PKG_CHECK_MODULES(WEBPDEMUX, libwebpdemux >= webp_required_version,,
+            [have_webp="no (WebP not built with libwebpdemux)"])
+        ],
+        [have_webp="no (WebP not built with libwebpmux)"])
+    ],
     [have_webp="no (WebP not found)"])
 fi