make: drop darwin-386 build target

Since we also dropped support for building binaries for the darwin 386
architecture in loop, we remove that build target in LiT as well.

Author: guggero

make/release_flags.mk

@@ -1,8 +1,7 @@
 VERSION_TAG = $(shell date +%Y%m%d)-01
 VERSION_CHECK = @$(call print, "Building master with date version tag")
 
-BUILD_SYSTEM = darwin-386 \
-darwin-amd64 \
+BUILD_SYSTEM = darwin-amd64 \
 linux-386 \
 linux-amd64 \
 linux-armv6 \