I know my mingw32-make builds are flawed :( I haven't been able to build it from cvs directly (there's cvs "dead" files that are needed by autoconf), and there seem to be no svn or git mirrors that are any more decent or usable.
Could you please try the "official" mingw-w64 make (which is just an old cvs checkout with I believe upstream patches) from here:http://sourceforge.net/projects/mingw-w64/files/External%20binary%20packages%20%28Win64%20hosted%29/make/make-3.82.90-20111115.zip/download
I have taken this source+patches since my 4.8-seh build and if this fixes the problem, that would be great. Otherwise I'd have to go hunting for other patches or a decent current snapshot of mingw32-make.
On a sidenote, I've had great success using Qt's jom.exe even for MinGW makefiles. It allows for unseen parallellism in a Qt build. Perhaps it is worth looking into solidifying its MinGW makefile support in the near future. I am all for leaving mingw32-make behind. It's old and unnecessarily slow.