testing: Do not ignore the return value of RUN_ALL_TESTS

Instead of ignoring the return value of RUN_ALL_TESTS, exit with the same status
code. This will make failing tests actually fail the build, instead of logging
the error, and then exiting successfully.

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

testing/setup-googletest.h

@@ -36,7 +36,6 @@
     /* Turn off virtual_io's input. */ \
     Kaleidoscope.device().keyScanner().setEnableReadMatrix(false); \
     testing::InitGoogleTest(); \
-    /* We assign the return value of RUN_ALL_TESTS, to */ \
-    /* silence a compiler warning. */                     \
-    int __ignore__ = RUN_ALL_TESTS();           \
+    int result = RUN_ALL_TESTS();           \
+    exit(result); \
   }