bigdecimal.c: refine macros

* ext/bigdecimal/bigdecimal.c (PUSH, SAVE): remove extra
  semicolons.

* ext/bigdecimal/bigdecimal.c (GUARD_OBJ): add parentheses and
  make an expression instead of a statement.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45002 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
ext/psych/yaml: suppress warnings

* ext/psych/yaml/emitter.c (WRITE_BREAK, PUT_BREAK): suppress
  unused-value warnings.

* ext/psych/yaml/parser.c, ext/psych/yaml/scanner.c: suppress
  unused-but-set-variable warnings.

* ext/psych/yaml/yaml_private.h (STACK_EMPTY): ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45003 b2dd03c8-39d4-4d8f-98ff-823fe69b080e