After upgrading to 3.15.2, ld won't link because crt2.o is missing. I noticed that such modules were installed to /usr/i686-mingw32/usr/lib64, but obviously they're not 64-bit modules. Copying everything in that directory back to /usr/i686-mingw32/usr/lib fixed the linking problems for me. Reproducible: Always Haven't looked into possible causes yet.
*** This bug has been marked as a duplicate of bug 261070 ***