Your log says that the problem occurred when you ran this:
gcc -std=gnu11 -DHAVE_CONFIG_H -DEXEEXT=\"\" -I. -I.. -g -O2 -MT fopen.lo -MD -MP -MF .deps/fopen.Tpo -c fopen.c -fPIC -DPIC -o .libs/fopen.o
Can you send us the preprocessor output? That is, the output of these commands: gcc -std=gnu11 -DHAVE_CONFIG_H -DEXEEXT=\"\" -I. -I.. -g -O2 -E fopen.c >fopen.i gzip fopen.iand then send us fopen.i.gz. That might help us debug the problem without your having to come up with a smaller reproducer.
