Merge branch 'chore/rename-xmrig-hac-to-drg-xmrig' into dev

Point the miner build at DragonX/drg-xmrig and rename the prebuilt staging
dir xmrig-hac -> drg-xmrig across setup.sh, build.sh, the legacy Windows
script, .gitignore and README.

.gitignore

@@ -11,8 +11,8 @@ prebuilt-binaries/dragonxd-win/*
 !prebuilt-binaries/dragonxd-win/.gitkeep
 prebuilt-binaries/dragonxd-mac/*
 !prebuilt-binaries/dragonxd-mac/.gitkeep
-prebuilt-binaries/xmrig-hac/*
-!prebuilt-binaries/xmrig-hac/.gitkeep
+prebuilt-binaries/drg-xmrig/*
+!prebuilt-binaries/drg-xmrig/.gitkeep
 
 
 # External sources / toolchains (created by scripts/setup.sh)
@@ -33,7 +33,7 @@ imgui.ini
 *.bak*
 *.params
 asmap.dat
-/external/xmrig-hac
+/external/drg-xmrig
 /memory
 /todo.md
 /.github/