package/mpc: bump to version 1.2.1
Since version 1.2.0, mpc requires mpfr 4.1.0.
See https://gitlab.inria.fr/mpc/mpc/-/commit/bc3541daa63fb6f53a5ca422766ef420e3663f6a
Update indentation in hash file (two spaces).
Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>