Renamed scmp -> cmp

- enum lfs3_scmp -> enum lfs3_cmp
- cmp -> cmp

lfs3_scmp_t is still used as the type, as the s prefix indicates the
type is signed, usually for muxing with error codes.

I think that led to the enum also being named lfs3_scmp, but that's not
quite right.

But none of this really matters because enums are so useless and broken
in C.

lfs3.c

@@ -12,7 +12,7 @@
 // internally used disk-comparison enum
 //
 // note LT < EQ < GT
-enum lfs3_scmp {
+enum lfs3_cmp {
     LFS3_CMP_LT = 0, // disk < query
     LFS3_CMP_EQ = 1, // disk = query
     LFS3_CMP_GT = 2, // disk > query