Adding -D UNITY_OUTPUT_CHAR=putcharSpy to testing build targets

Updated clang and gcc targets. Fixed spelling of LIMITS, which breaks the
  gcc_auto_sizeof.yml build.
 Commented -Wunreachable-code, Unity won't build on OSX clang with it,
  error in unity.c:769 & 932: 'default: break;' case.

test/targets/gcc_auto_stdint.yml

@@ -32,6 +32,7 @@ compiler:
   defines:
     prefix: '-D'
     items:
+      - UNITY_OUTPUT_CHAR=putcharSpy
       - UNITY_INCLUDE_DOUBLE
       - UNITY_SUPPORT_TEST_CASES
       - UNITY_SUPPORT_64