Fix Guile li_std_string testcase which requires a UTF-8 locale set

This was failing on Mac OSX and is a further fix to
43c8f2351c to fix #139

Examples/test-suite/guile/li_std_string_runme.scm

@@ -3,7 +3,30 @@
 ;; current module.  That's enough for such a simple test.
 (dynamic-call "scm_init_li_std_string_module" (dynamic-link "./libli_std_string"))
 ; Note: when working with non-ascii strings in guile 2
-;       locale must be set explicitly
+;       Guile doesn't handle non-ascii characters in the default C locale
+;       The locale must be set explicitly
 ;       The setlocale call below takes care of that
-(setlocale LC_ALL "en_US.utf8")
+;       The locale needs to be a UTF-8 locale to handle the non-ASCII characters
+;       But they are named differently on different systems so we try a few until one works
+
+(define (try-set-locale name)
+;  (display "testing ")
+;  (display name)
+;  (display "\n")
+  (catch #t
+    (lambda ()
+      (setlocale LC_ALL name)
+      #t
+    )
+    (lambda (key . parameters)
+      #f
+    ))
+)
+
+(if (not (try-set-locale "C.UTF-8"))     ; Linux
+(if (not (try-set-locale "en_US.utf8"))  ; Linux
+(if (not (try-set-locale "en_US.UTF-8")) ; Mac OSX
+(error "Failed to set any UTF-8 locale")
+)))
+
 (load "../schemerunme/li_std_string.scm")