patch 8.2.1973: finding a patch number can be a bit slow

Problem:    Finding a patch number can be a bit slow.
Solution:   Use binary search. (closes #7279)

Author: brammool

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1973,
 /**/
     1972,
 /**/
@@ -4725,11 +4727,21 @@ highest_patch(void)
     int
 has_patch(int n)
 {
-    int		i;
+    int		h, m, l;
 
-    for (i = 0; included_patches[i] != 0; ++i)
-	if (included_patches[i] == n)
+    // Perform a binary search.
+    l = 0;
+    h = (int)(sizeof(included_patches) / sizeof(included_patches[0])) - 1;
+    while (l < h)
+    {
+	m = (l + h) / 2;
+	if (included_patches[m] == n)
 	    return TRUE;
+	if (included_patches[m] < n)
+	    h = m;
+	else
+	    l = m + 1;
+    }
     return FALSE;
 }
 #endif
@@ -4941,9 +4953,7 @@ list_version(void)
     {
 	msg_puts(_("\nIncluded patches: "));
 	first = -1;
-	// find last one
-	for (i = 0; included_patches[i] != 0; ++i)
-	    ;
+	i = (int)(sizeof(included_patches) / sizeof(included_patches[0])) - 1;
 	while (--i >= 0)
 	{
 	    if (first < 0)