patch 9.0.1405: missing check for out-of-memory

Problem:    Missing check for out-of-memory.
Solution:   Check for alloc() returning NULL pointer. (closes #12149)

src/option.c

@@ -126,7 +126,6 @@ set_init_default_backupskip(void)
 #endif
     int		len;
     garray_T	ga;
-    int		mustfree;
     char_u	*item;
 
     opt_idx = findoption((char_u *)"backupskip");
@@ -134,7 +133,7 @@ set_init_default_backupskip(void)
     ga_init2(&ga, 1, 100);
     for (n = 0; n < (long)ARRAY_LENGTH(names); ++n)
     {
-	mustfree = FALSE;
+	int		mustfree = FALSE;
 #ifdef UNIX
 	if (*names[n] == NUL)
 # ifdef MACOS_X
@@ -150,6 +149,8 @@ set_init_default_backupskip(void)
 	    // First time count the NUL, otherwise count the ','.
 	    len = (int)STRLEN(p) + 3;
 	    item = alloc(len);
+	    if (item != NULL)
+	    {
 		STRCPY(item, p);
 		add_pathsep(item);
 		STRCAT(item, "*");
@@ -164,6 +165,7 @@ set_init_default_backupskip(void)
 		}
 		vim_free(item);
 	    }
+	}
 	if (mustfree)
 	    vim_free(p);
     }

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1405,
 /**/
     1404,
 /**/