`All-required-libraries` section in WIKI can be improve and updated for raspberrypi

All code code from All-required-libraries for Debian is works on Raspbian OS too, the bdwgc installation works too.

root@raspberrypi:~/crystal# uname -a
Linux raspberrypi 4.19.50+ #1 Tue Nov 26 01:49:16 CET 2019 armv6l GNU/Linux

But, there exists some issues:

  1. make -j no core number, is invalid in PI, i guess this is a typo?
root@raspberrypi:~/bdwgc# make -j
make[1]: Entering directory '/root/bdwgc'
make[1]: Leaving directory '/root/bdwgc'
  1. Clone all code into local is really slow from China and not necessary, so use --depth=1 is reasonable.
git clone --depth=1 https://github.com/ivmai/bdwgc.git

clone to a specified tag is possible.

git clone --branch 1.5.0 --depth 1 https://github.com/crystal-lang/crystal