[monero-project/monero] One build directory per branch/arch. (#4286)

moneromooo-monero commented on this pull request.

> all: release-all

cmake-debug:
— mkdir -p build/debug
— cd build/debug && cmake -D CMAKE_BUILD_TYPE=Debug ../..
+ mkdir -p build/$(subbuilddir)/debug
+ cd build/$(subbuilddir)/debug && cmake -D CMAKE_BUILD_TYPE=Debug ../../../..

And replacing / with something else (I do have a branch with a / in so it’s not pedantic :P)