gdc 0.20 svn branch on mingw/gcc4.0.3 (win32) segfaults

[Downs]

Attempting to build the current rev48 gdc 0.20 branch on mingw/gcc4.0.3; 
the resulting gdc.exe is incapable of compiling even the most basic test 
files; it crashes on configure with a sigsegv in actest.d:0.
Somewhat related question; is it possible to compile gcc so that it does 
not catch segment violations internally? This "feature" makes it 
impossible for me to get stack traces of the crash in gdb (no stackdumps 
are produced either).
Alternatively, any idea what I could do to narrow the problem area down?
Thanks for ideas; greetings.