Use an "example" build tag instead of "ignore".

The golang-dev discussion is at
https://groups.google.com/d/topic/golang-dev/qKpxZiNABcY/discussion

example/capjoin/main.go

@@ -3,10 +3,11 @@
 // FreeType License or the GNU General Public License version 2 (or
 // any later version), both of which can be found in the LICENSE file.
 
-// +build ignore
+// +build example
 //
 // This build tag means that "go install github.com/golang/freetype/..."
-// doesn't install this example program. Use "go run main.go" to run it.
+// doesn't install this example program. Use "go run main.go" to run it or "go
+// install -tags=example" to install it.
 
 package main
 

example/drawer/main.go

@@ -3,10 +3,11 @@
 // FreeType License or the GNU General Public License version 2 (or
 // any later version), both of which can be found in the LICENSE file.
 
-// +build ignore
+// +build example
 //
 // This build tag means that "go install github.com/golang/freetype/..."
-// doesn't install this example program. Use "go run main.go" to run it.
+// doesn't install this example program. Use "go run main.go" to run it or "go
+// install -tags=example" to install it.
 
 package main
 

example/freetype/main.go

@@ -3,10 +3,11 @@
 // FreeType License or the GNU General Public License version 2 (or
 // any later version), both of which can be found in the LICENSE file.
 
-// +build ignore
+// +build example
 //
 // This build tag means that "go install github.com/golang/freetype/..."
-// doesn't install this example program. Use "go run main.go" to run it.
+// doesn't install this example program. Use "go run main.go" to run it or "go
+// install -tags=example" to install it.
 
 package main
 

example/gamma/main.go

@@ -3,10 +3,11 @@
 // FreeType License or the GNU General Public License version 2 (or
 // any later version), both of which can be found in the LICENSE file.
 
-// +build ignore
+// +build example
 //
 // This build tag means that "go install github.com/golang/freetype/..."
-// doesn't install this example program. Use "go run main.go" to run it.
+// doesn't install this example program. Use "go run main.go" to run it or "go
+// install -tags=example" to install it.
 
 package main
 

example/raster/main.go

@@ -3,10 +3,11 @@
 // FreeType License or the GNU General Public License version 2 (or
 // any later version), both of which can be found in the LICENSE file.
 
-// +build ignore
+// +build example
 //
 // This build tag means that "go install github.com/golang/freetype/..."
-// doesn't install this example program. Use "go run main.go" to run it.
+// doesn't install this example program. Use "go run main.go" to run it or "go
+// install -tags=example" to install it.
 
 package main
 

example/round/main.go

@@ -3,10 +3,11 @@
 // FreeType License or the GNU General Public License version 2 (or
 // any later version), both of which can be found in the LICENSE file.
 
-// +build ignore
+// +build example
 //
 // This build tag means that "go install github.com/golang/freetype/..."
-// doesn't install this example program. Use "go run main.go" to run it.
+// doesn't install this example program. Use "go run main.go" to run it or "go
+// install -tags=example" to install it.
 
 // This program visualizes the quadratic approximation to the circle, used to
 // implement round joins when stroking paths. The approximation is used in the

example/truetype/main.go

@@ -3,10 +3,11 @@
 // FreeType License or the GNU General Public License version 2 (or
 // any later version), both of which can be found in the LICENSE file.
 
-// +build ignore
+// +build example
 //
 // This build tag means that "go install github.com/golang/freetype/..."
-// doesn't install this example program. Use "go run main.go" to run it.
+// doesn't install this example program. Use "go run main.go" to run it or "go
+// install -tags=example" to install it.
 
 package main