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)
diff --git a/src/version.c b/src/version.c
index 2a54dc9..e70a0f9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    348,
+/**/
     347,
 /**/
     346,