[QBS] Follow-up on reproducible builds

[Stephan Gatzka]

Hi,

We still lack a test for reproducible builds. I asked the gcc guys and
got the answer, that pretty much anything compiled with -flto leads to
different binaries.

So I tried it out:
cat a.c:
int bar (void) { return 0; }

gcc -flto -c -o a1.o a.c
gcc -flto -c -o a2.o a.c
diff a1.o a2.o
Binary files a1.o and a2.o differ

gcc -flto -c -frandom-seed=123 -o a1.o a.c
gcc -flto -c -frandom-seed=123 -o a2.o a.c
diff a1.o a2.o

Unfortunately, this example only works for gcc, not clang. Clang still
produces identical binaries.

Regards,

Stephan