Declare statfs MAGIC constants as c_uint on s390x
Declare statfs MAGIC constants as c_uint on s390x

Previously, statfs MAGIC constants like EXT4_SUPER_MAGIC were defined as c_long
for linux-gnu, whereas a statfs f_type is a c_uint on s390x. This commit
exempts these definitions from s390x and instead defines these constants as
c_uint on s390x. This is safe as none of these constants are wider than 32bit.

Signed-off-by: Jakob Naucke <f801fe1c7395a0227553edf39f0891adceb2f435@ibm.com>

rust-lang/libc,rust-lang/libc,rust-lang/libc