If called without -T or -t, fsck attempts to detect the
file system type.  If this fails, fsck will fail with
"unknown file system type" message.

PR:		188214
Allow CC to not actually exist. During the ports INDEX run, all the
Makefiles are evaluated without building things. In a normal build,
the prerequisites would be built, and CC would be an actual thing. In
an INDEX build, though, they don't exists. Redirect stderr to get rid
of annoying messages, and assume that the compiler version is 0 if the
actual compiler can't tell us. Do this in preference to guessing based
on numbers because gcc410 might be 4.10, or 4.1.0 and without
carefully crafted special knowledge we differentiate between them
easily (also ming-gcc has no clues at all). Elsewhere, don't trust
the compiler version if it is 0.