Remove -Wno-parentheses-equality from gcc --strict-warnings options.

There has never been any gcc option of that kind.
Reviewed-by: NAndy Polyakov <appro@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2705)

Configure

@@ -124,7 +124,6 @@ my $gcc_devteam_warn = "-DDEBUG_UNUSED"
         . " -Wshadow"
         . " -Wformat"
         . " -Wtype-limits"
-        . " -Wno-parentheses-equality"
         . " -Werror"
         ;