patch 8.1.0023: gcc 8.1 warns for use of strncpy()

Problem:    gcc 8.1 warns for use of strncpy(). (John Marriott)
Solution:   Use mch_memmove() instead of STRNCPY().

Author: brammool

src/memline.c

@@ -344,7 +344,7 @@ ml_open(buf_T *buf)
     b0p->b0_magic_int = (int)B0_MAGIC_INT;
     b0p->b0_magic_short = (short)B0_MAGIC_SHORT;
     b0p->b0_magic_char = B0_MAGIC_CHAR;
-    STRNCPY(b0p->b0_version, "VIM ", 4);
+    mch_memmove(b0p->b0_version, "VIM ", 4);
     STRNCPY(b0p->b0_version + 4, Version, 6);
     long_to_char((long)mfp->mf_page_size, b0p->b0_page_size);
 

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    23,
 /**/
     22,
 /**/