Update build.bat to be in sync with build.sh

`build.bat` fails to compile `dcd-server`.

This PR fixes this issue and it also makes `build.bat` more similar to `build.sh`, using `cmd`'s "`^`" trick.
  
In the process, I found that `dcd-server` fails to build using both `-O` and `-inline` at the same time (with error message `Internal error: backend\cgcod.c 1594` using DMD 2.066-b6).
Same thing with DMD 2.065 (only the line number is different).

Removing -O or -inline solves the problem (I chose the latter).

Also, `dscanner` path were included in both `build.sh` and `build.bat`. Changed to `libdparse/src`.