Fix subproject gtest

Testing doesn't seem to be enabled if gtest isn't present.  Resolve the
flows in meson.

Tested: without gtest installed, 'meson builddir' starts and runs unit
tests as expected.

Change-Id: Ie95bee7f429a4878083272a9886ea4c3d9977350
Signed-off-by: Ed Tanous <etanous@nvidia.com>
diff --git a/meson.build b/meson.build
index 7ba474c..58433bb 100644
--- a/meson.build
+++ b/meson.build
@@ -17,7 +17,6 @@
     '-DBOOST_ALL_NO_LIB',
     '-DBOOST_ALLOW_DEPRECATED_HEADERS',
 ]
-build_tests = get_option('tests')
 cpp = meson.get_compiler('cpp')
 boost = dependency('boost', required: false)
 if not boost.found()
@@ -116,11 +115,11 @@
 subdir('service_files')
 subdir('src')
 
-if not build_tests.disabled()
+if get_option('tests').allowed()
     test_boost_args = boost_args + ['-DBOOST_ASIO_DISABLE_THREADS']
     gtest = dependency('gtest', main: true, disabler: true, required: false)
     gmock = dependency('gmock', disabler: true, required: false)
-    if not (gtest.found() and gmock.found()) and build_tests.enabled()
+    if not (gtest.found() and gmock.found())
         cmake = import('cmake')
         gtest_subproject = cmake.subproject('gtest')
         cm_gtest = gtest_subproject.dependency('gtest')