cmake: fix formatting typo

cmake-format does not recognize the directive without the space. This
causes later versions to drop the entire block:
https://github.com/cheshirekow/cmake_format/issues/65

Change-Id: I78bd31698c7ded3f9027279d6dd4e3c6aeaae924

test/test.cmake

diff --git a/test/test.cmake b/test/test.cmake
index 8594d05..7b58488 100644
--- a/test/test.cmake
+++ b/test/test.cmake
@@ -405,7 +405,7 @@
         OR (CONFIG_AV1_DECODER AND  "${var}" MATCHES "_TEST_DECODER_"))
       list(APPEND aom_test_source_vars ${var})
     endif()
-    # cmake-format:on
+    # cmake-format: on
   endforeach()
 
   # Libaom_test_srcs.txt generation.