chase-symlinks: Rename chase_symlinks() to chase()

Chasing symlinks is a core function that's used in a lot of places
so it deservers a less verbose names so let's rename it to chase()
and chaseat().

We also slightly change the pattern used for the chaseat() helpers
so we get chase_and_openat() and similar.

src/basic/mountpoint-util.c

@@ -8,7 +8,7 @@
 #endif
 
 #include "alloc-util.h"
-#include "chase-symlinks.h"
+#include "chase.h"
 #include "fd-util.h"
 #include "fileio.h"
 #include "filesystems.h"
@@ -341,7 +341,7 @@ int path_is_mount_point(const char *t, const char *root, int flags) {
          * /bin -> /usr/bin/ and /usr is a mount point, then the parent that we
          * look at needs to be /usr, not /. */
         if (flags & AT_SYMLINK_FOLLOW) {
-                r = chase_symlinks(t, root, CHASE_TRAIL_SLASH, &canonical, NULL);
+                r = chase(t, root, CHASE_TRAIL_SLASH, &canonical, NULL);
                 if (r < 0)
                         return r;