configure.in: suppress warnings

* configure.in (warnflags): suppress warnings caused by macro
  expansion with clang.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53592 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

configure.in

@@ -815,6 +815,9 @@ if test "$GCC:${warnflags+set}:no" = yes::no; then
     for wflag in -Wno-unused-parameter -Wno-parentheses -Wno-long-long \
                  -diag-disable=2259 \
 		 -Wno-missing-field-initializers \
+		 -Wno-tautological-compare \
+		 -Wno-parentheses-equality \
+		 -Wno-constant-logical-operand \
 		 -Wunused-variable \
 		 -Werror=pointer-arith \
 		 -Werror=write-strings \