Added in 4d39b70166 without explanation as
to why.
We also revbump to rebuild the binary. On x86_64-musl, old libz.so,
built with gcc 7, is using a 2132KB RE mmap when dynamically linked,
probably because of a 0x200000 alignment required for the RE section.
After rebuilding, 96KB are used, with the actual RE mmap reduced to 56K.
The new alignment is 0x1000.
9dc9a42eb7