.gitignore: import from upsilon_docker

.gitignore

@@ -34,3 +34,15 @@ firmware/rtl/raster/yosys_output
 firmware/csr_bitwidth.json
 boot/*
 !boot/boot.json
+build/buildroot.tar.gz
+build/buildroot/
+build/f4pga/
+build/litex/
+build/opensbi/
+build/upsilon/
+build/upsilon.tar.gz
+build/f4pga.tar.gz
+build/opensbi.tar.gz
+build/upsilon-opensbi.tar.gz
+build/upsilon-hardware.tar.gz
+build/upsilon-buildroot.tar.gz