BUG#10687 - Merge engine fails under Windows

This final cset is to fix a syntax problem in ha_myisammrg.cc where a / was left out of a format string.
It also adds a check in has_path to avoid a possible redundant comparison.

ha_myisammrg.cc:
  Replaced missing / in format string
my_getwd.c:
  Added test to see if FN_LIBCHAR != '/' before doing comparison to avoid redundant comparison

mysys/my_getwd.c

@@ -208,7 +208,10 @@ int test_if_hard_path(register const char *dir_name)
 
 my_bool has_path(const char *name)
 {
-  return test(strchr(name, FN_LIBCHAR)) || test(strchr(name,'/'))
+  return test(strchr(name, FN_LIBCHAR)) 
+#if FN_LIBCHAR != '/'
+    || test(strchr(name,'/'))
+#endif
 #ifdef FN_DEVCHAR
     || test(strchr(name, FN_DEVCHAR))
 #endif

sql/ha_myisammrg.cc

@@ -406,7 +406,7 @@ int ha_myisammrg::create(const char *name, register TABLE *form,
         This means that it might not be possible to move the DATADIR of
         an embedded server without changing the paths in the .MRG file.
       */
-      uint length= my_snprintf(buff, FN_REFLEN, "%s%s/%s", mysql_data_home,
+      uint length= my_snprintf(buff, FN_REFLEN, "%s/%s/%s", mysql_data_home,
 			       tables->db, tables->real_name);
       /*
         If a MyISAM table is in the same directory as the MERGE table,