Ability to overwrite go binary path when building.

Fixes #9.

scripts/build.sh

@@ -2,6 +2,8 @@
 
 # Metricator build script.
 
+GO=${GO:=$(which go)}
+
 source ./scripts/shell_helpers/get_git_data.sh
 
 WHATTOBUILD=$1
@@ -13,5 +15,7 @@ LINKERFLAGS="\
 -X go.dev.pztrn.name/metricator/internal/common.Version=${VERSION}"
 
 
+echo "Using $(go version) at ${GO}"
+
 cd cmd/${WHATTOBUILD}
 go build -tags netgo -ldflags "${LINKERFLAGS} -w -extldflags '-static'" -o ../../._bin/${WHATTOBUILD}