CLEANUP: Do not use a fixed type for 'sizeof' in 'calloc'

Changes performed using the following coccinelle patch:

    @@
    type T;
    expression E;
    expression t;
    @@

    (
      t = calloc(E, sizeof(*t))
    |
    - t = calloc(E, sizeof(T))
    + t = calloc(E, sizeof(*t))
    )

Looking through the commit history, grepping for coccinelle shows that the same
replacement with a different patch was already performed in the past in commit
02779b6263a177b1e462e53db6eaf57bcda574bc.
diff --git a/src/tools.c b/src/tools.c
index b5cc30e..803afab 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -2236,7 +2236,7 @@
 	len = len >> 1;
 
 	if (!*binstr) {
-		*binstr = calloc(len, sizeof(char));
+		*binstr = calloc(len, sizeof(**binstr));
 		if (!*binstr) {
 			memprintf(err, "out of memory while loading string pattern");
 			return 0;