brew-pull: avoid the "var = ... rescue nil" dance
leptonica 1.71

Closes #30621.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
leptonica: update 1.71 bottle.
libsodium: use pkg-config

use pkg-config to force .pc

Closes #30681
libsodium: update 0.6.0_1 bottle.