error.c: Let Exception#inspect inspect its message

... only when the message string has a newline.

`p StandardError.new("foo\nbar")` now prints `#<StandardError: "foo\nbar">'
instead of:

    #<StandardError:
    bar>

[Bug #18170]

1 files changed, 1 insertions, 1 deletions

diff --git a/string.c b/string.c
index 83d90ff3a9..9c37d774b3 100644
--- a/string.c
+++ b/string.c
@@ -6376,7 +6376,7 @@ rb_str_reverse_bang(VALUE str)
  *
  */
 
-static VALUE
+VALUE
 rb_str_include(VALUE str, VALUE arg)
 {
     long i;