[msvc] Customize the stack size

Or it crashes in a lot of cases when running rebol-test

The size comes from the mingw makefile
Do not use the system qsort

The implementation varies on different platforms (it seems to be stable
sort on Linux, while unstable on Windows).

sort ["a" "A"] gives different result on these platforms when using the
system qsort

Rename it to reb_qsort to avoid conflict when linking. It seems to be
easy to redefine the system function, but not as easy for visual studio.
As its usage is quite limited, it's easier to rename it.
[msvc] Compile f-qsort.c
Chnage mode
Enable #[datatype] constructor for struct! and routine!

callback! needs an alias MT_Callback to MT_Routine to make it work, so
it's not enabled yet.
Fix crash in enline

demo'ed by this code:
>> enline "^/a^/b"