patch 8.0.0348: using shadow dir on Mac lack +clipboard

Problem:    When building with a shadow directory on macOS lacks the
            +clipboard feature.
Solution:   Link *.m files, specifically os_macosx.m. (Kazunobu Kuriyama)

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    348,
 /**/
     347,
 /**/