testing/chez-scheme: time_t size failure on x86

chez-scheme fails to build on x86, due to the musl-1.2 time_t changes:

sizeof(time_t) * 8 [8] != time_t_bits [32]
make[4]: *** [Mf-base:340: cmacros.so] Error 1
make[4]: *** [Mf-base:377: nanopass.so] Error 1

I also noticed that the build() phases misses a make invocation.

See: https://build.alpinelinux.org/buildlogs/build-edge-x86/testing/chez-scheme/chez-scheme-9.5.2-r0.log