[BRLTTY] Broken build system?

[Mario Lang]

Hi.

I can not build brltty from svn anymore, after a fresh checkout
./autogen
./configure
I get the following behaviour from make:
x2:/tmp/brltty% make
Makefile:32: .config.mk: No such file or directory
make: *** No rule to make target `.config.mk'.  Stop.
zsh: exit 2     make

This is because BLD_TOP is set to "." and the include in prologue.mk.in
does direct concatenation without a slash.  However, I was not
able to determine what exactly causes this strange breakage.
-- 
CYa,
  Mario