separate m44 tests

Change-Id: I33db5286538cd5721ad0cf6095eef82c42ff1e35
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/283916
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/gn/tests.gni b/gn/tests.gni
index b30f944..f7bbdc7 100644
--- a/gn/tests.gni
+++ b/gn/tests.gni
@@ -142,6 +142,7 @@
   "$_tests/LRUCacheTest.cpp",
   "$_tests/LayerDrawLooperTest.cpp",
   "$_tests/LazyProxyTest.cpp",
+  "$_tests/M44Test.cpp",
   "$_tests/MD5Test.cpp",
   "$_tests/MallocPixelRefTest.cpp",
   "$_tests/MaskCacheTest.cpp",