[babl] meson build: clean up library dependency check

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

commit b7920c85052f18bdbbcd58b390e4be2ed3dceebf
Author: John Marshall <jtm home gmail com>
Date:   Mon Jun 11 09:51:27 2018 +0100

    meson build: clean up library dependency check

 meson.build | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
---
diff --git a/meson.build b/meson.build
index ab1d042..30fb035 100644
--- a/meson.build
+++ b/meson.build
@@ -281,15 +281,18 @@ else
 endif
 
 math = cc.find_library('m',   required: false)
-log  = cc.find_library('log', required: false)
+thread = dependency('threads',  required: false)
+if platform_android
+  log  = cc.find_library('log', required: false)
+else
+  log = []
+endif
 if platform_win32 
   dl = []
 else
   dl = cc.find_library('dl',  required: false)
 endif
 
-thread = dependency('threads',  required: false)
-
 
 ################################################################################
 # Build utilities