[gdk-pixbuf] Fix build on non-linux systems after commit b07c3bffffefb8573ad9ffcf926c07cb9f93d08b

[Matthias Clasen <matthiasc src gnome org>]

commit 844bf5d40cce33a75088a6c5ab1bc82970fbfa0b
Author: Yaakov Selkowitz <yselkowi redhat com>
Date:   Tue Sep 1 17:23:06 2015 -0500

    Fix build on non-linux systems after commit b07c3bffffefb8573ad9ffcf926c07cb9f93d08b
    
    https://bugzilla.gnome.org/show_bug.cgi?id=754154

 tests/Makefile.am |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 01d8e42..d5dca44 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -18,10 +18,15 @@ LDADD = \
 
 noinst_PROGRAMS +=                     \
        pixbuf-read                     \
-       pixbuf-lowmem                   \
        pixbuf-random                   \
        $(NULL)
 
+if OS_LINUX
+noinst_PROGRAMS +=                     \
+       pixbuf-lowmem                   \
+       $(NULL)
+endif
+
 test_programs =                        \
        animation                       \
        cve-2015-4491                   \