[mutter] meson: Do not install cogl config.env if installed tests are disabled

[Marco Trevisan <marcotrevi src gnome org>]

commit dbe73c3296b2818520606882961092c394d34f94
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Wed Jan 16 23:54:42 2019 +0100

    meson: Do not install cogl config.env if installed tests are disabled
    
    Until meson 0.50, setting the install parameter in 'configure_file' is ignored
    if 'install_dir' is set. Then until mutter doesn't depend on such meson version
    cogl_installed_tests_libexecdir should be empty unless have_installed_tests is
    false, or this file will be installed anyway.
    
    See https://github.com/mesonbuild/meson/issues/4160

 cogl/tests/meson.build | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/cogl/tests/meson.build b/cogl/tests/meson.build
index 784bd7d26..5284fe69f 100644
--- a/cogl/tests/meson.build
+++ b/cogl/tests/meson.build
@@ -4,10 +4,17 @@ cdata = configuration_data()
 cdata.set('HAVE_GL', have_gl.to_int())
 cdata.set('HAVE_GLES2', have_gles2.to_int())
 
-cogl_installed_tests_libexecdir = join_paths(
-  mutter_installed_tests_libexecdir, 'cogl', 'conform')
+# Until meson 0.50 setting the install parameter in 'configure_file' is ignored
+# if 'install_dir' is set, then until mutter doesn't depend on such meson version
+# cogl_installed_tests_libexecdir should be empty unless have_installed_tests
+# is false, or this file will be installed anyway.
+#
+# See https://github.com/mesonbuild/meson/issues/4160
+cogl_installed_tests_libexecdir = ''
 
 if have_installed_tests
+  cogl_installed_tests_libexecdir = join_paths(
+    mutter_installed_tests_libexecdir, 'cogl', 'conform')
   install_data('run-tests.sh', install_dir: cogl_installed_tests_libexecdir)
 endif