v.generalize: Initialize all of structure contents before using it (#…

…4281)

* v.generalize: Initialize all of structure contents before using it

Currently, in `head` which is a `POINT_LIST` structure, we are
only initializing the next pointer to NULL, but data present
in the point substructure is not initialized which implies that
it would be filled with random data. To avoid such scenario,
initialize point coordinates to zero.

This was found using cppcheck tool.

Signed-off-by: Mohan Yelugoti <ymdatta.work@gmail.com>

* Use correct literal for double type

Co-authored-by: Nicklas Larsson <n_larsson@yahoo.com>

---------

Signed-off-by: Mohan Yelugoti <ymdatta.work@gmail.com>
Co-authored-by: Nicklas Larsson <n_larsson@yahoo.com>

vector/v.generalize/smoothing.c

@@ -422,6 +422,7 @@ int hermite(struct line_pnts *Points, double step, double angle_thresh,
     angle_thresh *= M_PI / 180.0;
 
     head.next = NULL;
+    head.p.x = head.p.y = head.p.z = 0.0;
     point = last = &head;
 
     if (!is_loop) {