Add gb package

Remove build dependency

packages/gb.rb

@@ -0,0 +1,44 @@
+require 'package'
+
+class Gb < Package
+  description 'A project based build tool for the Go programming language.'
+  homepage 'https://getgb.io/'
+  version '0.4.4'
+  source_url 'https://github.com/constabulary/gb/archive/v0.4.4.tar.gz'
+  source_sha256 'c7993ae1994ad85cbe35b833d36a137772599fe7ed720edec2d76ebf3fc4313b'
+
+  binary_url ({
+  })
+  binary_sha256 ({
+  })
+
+  depends_on 'go'
+
+  def self.install
+    system "SAVEGOPATH=$GOPATH && \
+            export GOPATH=#{CREW_DEST_PREFIX}/share/gb && \
+            go get -v github.com/constabulary/gb/... && \
+            export GOPATH=$SAVEGOPATH"
+    system "mkdir -p #{CREW_DEST_PREFIX}/bin"
+    FileUtils.cd("#{CREW_DEST_PREFIX}/bin") do
+      system "echo '#!/bin/bash' > gb"
+      system "echo 'if [ -z \"\$GOPATH\" ]; then' >> gb"
+      system "echo '  echo \"GOPATH environment variable not set.\"' >> gb"
+      system "echo '  exit 1' >> gb"
+      system "echo 'fi' >> gb"
+      system "echo 'cd #{CREW_PREFIX}/share/gb' >> gb"
+      system "echo 'bin/gb \"\$@\"' >> gb"
+      system "echo 'cd -' >> gb"
+      system "chmod +x gb"
+      system "echo '#!/bin/bash' > gb-vendor"
+      system "echo 'if [ -z \"\$GOPATH\" ]; then' >> gb-vendor"
+      system "echo '  echo \"GOPATH environment variable not set.\"' >> gb-vendor"
+      system "echo '  exit 1' >> gb-vendor"
+      system "echo 'fi' >> gb-vendor"
+      system "echo 'cd #{CREW_PREFIX}/share/gb' >> gb-vendor"
+      system "echo 'bin/gb-vendor \"\$@\"' >> gb-vendor"
+      system "echo 'cd -' >> gb-vendor"
+      system "chmod +x gb-vendor"
+    end
+  end
+end