fix(stream): Respect 'test' feature

We were putting it into the generated code, not our code, causing it to
be an "unexpected cfg".

It would be nice to use the macro's cfgs in the generated code...

crates/anstream/src/_macros.rs

@@ -60,7 +60,7 @@
 #[macro_export]
 macro_rules! print {
     ($($arg:tt)*) => {{
-        if cfg!(any(feature = "test", test)) {
+        if cfg!(test) || $crate::_macros::FEATURE_TEST_ACTIVATED {
             let target_stream = std::io::stdout();
             let buffer = $crate::_macros::to_adapted_string(&format_args!($($arg)*), &target_stream);
             ::std::print!("{}", buffer)
@@ -132,7 +132,7 @@ macro_rules! println {
         $crate::print!("\n")
     };
     ($($arg:tt)*) => {{
-        if cfg!(any(feature = "test", test)) {
+        if cfg!(test) || $crate::_macros::FEATURE_TEST_ACTIVATED {
             let target_stream = std::io::stdout();
             let buffer = $crate::_macros::to_adapted_string(&format_args!($($arg)*), &target_stream);
             ::std::println!("{}", buffer)
@@ -183,7 +183,7 @@ macro_rules! println {
 #[macro_export]
 macro_rules! eprint {
     ($($arg:tt)*) => {{
-        if cfg!(any(feature = "test", test)) {
+        if cfg!(test) || $crate::_macros::FEATURE_TEST_ACTIVATED {
             let target_stream = std::io::stderr();
             let buffer = $crate::_macros::to_adapted_string(&format_args!($($arg)*), &target_stream);
             ::std::eprint!("{}", buffer)
@@ -237,7 +237,7 @@ macro_rules! eprintln {
         $crate::eprint!("\n")
     };
     ($($arg:tt)*) => {{
-        if cfg!(any(feature = "test", test)) {
+        if cfg!(test) || $crate::_macros::FEATURE_TEST_ACTIVATED {
             let target_stream = std::io::stderr();
             let buffer = $crate::_macros::to_adapted_string(&format_args!($($arg)*), &target_stream);
             ::std::eprintln!("{}", buffer)
@@ -343,6 +343,9 @@ macro_rules! panic {
     }};
 }
 
+#[cfg(feature = "auto")]
+pub const FEATURE_TEST_ACTIVATED: bool = cfg!(feature = "test");
+
 #[cfg(feature = "auto")]
 pub fn to_adapted_string(
     display: &dyn std::fmt::Display,