cmake: move test enablement into test cmake

CMakeLists.txt

@@ -111,7 +111,6 @@ include(DefaultCFlags)
 add_subdirectory(src)
 
 if(BUILD_TESTS)
-	enable_testing()
 	add_subdirectory(tests)
 endif()
 

tests/CMakeLists.txt

@@ -62,6 +62,8 @@ function(ADD_CLAR_TEST name)
 	endif()
 endfunction(ADD_CLAR_TEST)
 
+enable_testing()
+
 add_clar_test(offline             -v -xonline)
 add_clar_test(invasive            -v -score::ftruncate -sfilter::stream::bigfile -sodb::largefiles -siterator::workdir::filesystem_gunk -srepo::init -srepo::init::at_filesystem_root)
 add_clar_test(online              -v -sonline -xonline::customcert)