Fix stack overflow of bash when copying tf headers

[mareikethies]

Fixes issue described in #87. Putting together the copy command for tf headers in tf_configure.bzl using " && " causes a stack overflow in msys2 bash.exe on windows. Executing each copy as a single command (via "\n") prevents this.

[maxrohleder]

I experienced the same issue on powershell with msys2 base.exe enabled. With the proposed changes, it works like a charm.

I would never have discovered the stackoverflow as this line:

     0 [] bash 1410 cygwin_exception::open_stackdumpfile: Dumping stack trace to bash.exe.stackdump

was missing in the log on powershell...

Thank you so much for this @mareikethies!

[akmaier]

This would also totally help my project! There might be other issues down the line and we would be glad to track and fix them!