patch 8.0.1496: clearing a pointer takes two lines

Problem:    Clearing a pointer takes two lines.
Solution:   Add VIM_CLEAR() and replace vim_clear(). (Hirohito Higashi,
            closes #2629)
diff --git a/src/if_cscope.c b/src/if_cscope.c
index 4bf28ad..e4bcb51 100644
--- a/src/if_cscope.c
+++ b/src/if_cscope.c
@@ -1479,8 +1479,7 @@
     {
 	if ((csinfo[i].ppath = (char *)alloc((unsigned)strlen(ppath) + 1)) == NULL)
 	{
-	    vim_free(csinfo[i].fname);
-	    csinfo[i].fname = NULL;
+	    VIM_CLEAR(csinfo[i].fname);
 	    return -1;
 	}
 	(void)strcpy(csinfo[i].ppath, (const char *)ppath);
@@ -1491,10 +1490,8 @@
     {
 	if ((csinfo[i].flags = (char *)alloc((unsigned)strlen(flags) + 1)) == NULL)
 	{
-	    vim_free(csinfo[i].fname);
-	    vim_free(csinfo[i].ppath);
-	    csinfo[i].fname = NULL;
-	    csinfo[i].ppath = NULL;
+	    VIM_CLEAR(csinfo[i].fname);
+	    VIM_CLEAR(csinfo[i].ppath);
 	    return -1;
 	}
 	(void)strcpy(csinfo[i].flags, (const char *)flags);
@@ -1939,10 +1936,8 @@
     if (totsofar == 0)
     {
 	/* No matches, free the arrays and return NULL in "*matches_p". */
-	vim_free(matches);
-	matches = NULL;
-	vim_free(cntxts);
-	cntxts = NULL;
+	VIM_CLEAR(matches);
+	VIM_CLEAR(cntxts);
     }
     *matched = totsofar;
     *matches_p = matches;
@@ -2445,7 +2440,7 @@
 	if (csdir != NULL)
 	{
 	    vim_strncpy(csdir, (char_u *)csinfo[i].fname,
-		                       gettail((char_u *)csinfo[i].fname)
+					  gettail((char_u *)csinfo[i].fname)
 						 - (char_u *)csinfo[i].fname);
 	    len += (int)STRLEN(csdir);
 	}