[gegl] Restore math library in the Libs file of the gegl pkg-config file.

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 4708e5903ea6d0774dc3843afe360e843d23f5d2
Author: Koop Mast <kwm rainbow-runner nl>
Date:   Sun Dec 8 21:48:33 2019 +0100

    Restore math library in the Libs file of the gegl pkg-config file.

 meson.build | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/meson.build b/meson.build
index bda702b80..9496396b0 100644
--- a/meson.build
+++ b/meson.build
@@ -344,6 +344,7 @@ pkgconfig.generate(filebase: 'gegl-' + api_version,
   libraries: [
     gegl_lib,
     gegl_npd_lib,
+    math,
   ],
   subdirs: api_name,
 )