Add cross-compilation Makefile targets and tar-based releases.

Revamp the build system to be more inline with other Prometheus exporters.
Notably add Darwin and Windows build targets, and add support for releases
using tar files.

tools/vendor/github.com/mattn/goveralls/README.md

@@ -40,7 +40,7 @@ Enable Travis-CI on your github repository settings.
 
 For a **public** github repository put below's `.travis.yml`.
 
-```
+```yml
 language: go
 sudo: false
 go:
@@ -48,14 +48,14 @@ go:
 before_install:
   - go get github.com/mattn/goveralls
 script:
-  - $HOME/gopath/bin/goveralls -service=travis-ci
+  - $GOPATH/bin/goveralls -service=travis-ci
 ```
 
 For a **public** github repository, it is not necessary to define your repository key (`COVERALLS_TOKEN`).
 
 For a **private** github repository put below's `.travis.yml`. If you use **travis pro**, you need to specify `-service=travis-pro` instead of `-service=travis-ci`.
 
-```
+```yml
 language: go
 sudo: false
 go:
@@ -63,7 +63,7 @@ go:
 before_install:
   - go get github.com/mattn/goveralls
 script:
-  - $HOME/gopath/bin/goveralls -service=travis-pro
+  - $GOPATH/bin/goveralls -service=travis-pro
 ```
 
 Store your Coveralls API token in `Environment variables`.
@@ -81,7 +81,7 @@ $ travis encrypt COVERALLS_TOKEN=your_token_goes_here --add env.global
 
 travis will add `env` block as following example:
 
-```
+```yml
 env:
   global:
     secure: xxxxxxxxxxxxx

tools/vendor/github.com/mattn/goveralls/gocover.go

@@ -48,14 +48,13 @@ func mergeProfs(pfss [][]*cover.Profile) []*cover.Profile {
 	ret := make([]*cover.Profile, 0, len(head))
 	for i, profile := range head {
 		for _, ps := range rest {
+			// find profiles
 			if len(ps) == 0 {
-				// no test files
 				continue
 			} else if len(ps) < i+1 {
-				log.Fatal("Profile length is different")
-			}
-			if ps[i].FileName != profile.FileName {
-				log.Fatal("Profile FileName is different")
+				continue
+			} else if ps[i].FileName != profile.FileName {
+				continue
 			}
 			profile.Blocks = mergeProfBlocks(profile.Blocks, ps[i].Blocks)
 		}

tools/vendor/github.com/mattn/goveralls/goveralls.go

@@ -45,6 +45,7 @@ var (
 	extraFlags Flags
 	pkg        = flag.String("package", "", "Go package")
 	verbose    = flag.Bool("v", false, "Pass '-v' argument to 'go test' and output to stdout")
+	race       = flag.Bool("race", false, "Pass '-race' argument to 'go test'")
 	debug      = flag.Bool("debug", false, "Enable debug output")
 	coverprof  = flag.String("coverprofile", "", "If supplied, use a go cover profile (comma separated)")
 	covermode  = flag.String("covermode", "count", "sent as covermode argument to go test")
@@ -132,12 +133,18 @@ func getCoverage() ([]*SourceFile, error) {
 		outBuf := new(bytes.Buffer)
 		cmd.Stdout = outBuf
 		cmd.Stderr = outBuf
-
-		args := []string{"go", "test", "-covermode", *covermode, "-coverprofile", f.Name(), coverpkg}
+		coverm := *covermode
+		if *race {
+			coverm = "atomic"
+		}
+		args := []string{"go", "test", "-covermode", coverm, "-coverprofile", f.Name(), coverpkg}
 		if *verbose {
 			args = append(args, "-v")
 			cmd.Stdout = os.Stdout
 		}
+		if *race {
+			args = append(args, "-race")
+		}
 		args = append(args, extraFlags...)
 		args = append(args, line)
 		cmd.Args = args