configure stall in i686-pc-cygwin/libcpp, gcc 4.5 (building in cygwin 1.7)

[Tim Prince]

For several weeks, I have been seeing the gcc 4.5 builds terminating in 
libcpp with "cannot compute suffix of object files..."
In the configure.log, it starts complaining with
configure:2992 ..... "-V must come at the start of the command line" ... 
"unrecognized option '-qversion'"...
"xgcc: no input files"
Maybe this means nothing, but:
The next step reports failure of the compile test for suffix.
When I attempt to repeat the compile command shown, it gives no 
diagnostics, but sure enough the code returned to bash is 1.

If I run $HOME/libgcc/configure, it appears to configure OK, but when I 
run make in libcpp, it fails eventually when attempting to build 
addtf3.o (config/soft-fp/quad.h:63 error: unable to emulate 'TF'

So, the cygwin build has grown beyond my experience of how to work 
around its quirks.