Build tooling enhancements (#10429)

* Add LDFLAGS variable

* Replace curl by wget

* Revert "Replace curl by wget"

This reverts commit f40323c3d2e693f74a4a3f8705ab011feb3e378a.

* Use curl instead of wget

* Merge GO_LINKER_FLAGS into LDFLAGS

build/Dockerfile.buildenv

@@ -1,3 +1,3 @@
 FROM golang:1.12
 
-RUN apt-get update && apt-get install -y make git apt-transport-https ca-certificates curl software-properties-common build-essential zip wget xmlsec1
+RUN apt-get update && apt-get install -y make git apt-transport-https ca-certificates curl software-properties-common build-essential zip xmlsec1