Simplify static build, rely on go's cache

As of go 1.10, we do not need to explicitly build the stdlib for static
any more.  That happens automatically.  Timing tests show no discernible
difference between a `go install` with and without it.

Also use 'static' suffix instead of 'cgo'.

hack/lib/golang.sh

@@ -417,29 +417,6 @@ kube::golang::place_bins() {
   done
 }
 
-kube::golang::fallback_if_stdlib_not_installable() {
-  local go_root_dir=$(go env GOROOT);
-  local go_host_os=$(go env GOHOSTOS);
-  local go_host_arch=$(go env GOHOSTARCH);
-  local cgo_pkg_dir=${go_root_dir}/pkg/${go_host_os}_${go_host_arch}_cgo;
-
-  if [ -e ${cgo_pkg_dir} ]; then
-    return 0;
-  fi
-
-  if [ -w ${go_root_dir}/pkg ]; then
-    return 0;
-  fi
-
-  kube::log::status "+++ Warning: stdlib pkg with cgo flag not found.";
-  kube::log::status "+++ Warning: stdlib pkg cannot be rebuilt since ${go_root_dir}/pkg is not writable by `whoami`";
-  kube::log::status "+++ Warning: Make ${go_root_dir}/pkg writable for `whoami` for a one-time stdlib install, Or"
-  kube::log::status "+++ Warning: Rebuild stdlib using the command 'CGO_ENABLED=0 go install -a -installsuffix cgo std'";
-  kube::log::status "+++ Falling back to go build, which is slower";
-
-  use_go_build=true
-}
-
 # Builds the toolchain necessary for building kube. This needs to be
 # built only on the host platform.
 # TODO: Find this a proper home.
@@ -496,45 +473,38 @@ kube::golang::build_binaries_for_platform() {
     fi
   done
 
-  if [[ "${#statics[@]}" != 0 ]]; then
-      kube::golang::fallback_if_stdlib_not_installable;
-  fi
-
   if [[ -n ${use_go_build:-} ]]; then
-    kube::log::progress "    "
     for binary in "${statics[@]:+${statics[@]}}"; do
+      kube::log::info "  go build ${binary}"
       local outfile=$(kube::golang::output_filename_for_binary "${binary}" "${platform}")
       CGO_ENABLED=0 go build -o "${outfile}" \
         "${goflags[@]:+${goflags[@]}}" \
         -gcflags "${gogcflags}" \
         -ldflags "${goldflags}" \
         "${binary}"
-      kube::log::progress "*"
     done
     for binary in "${nonstatics[@]:+${nonstatics[@]}}"; do
+      kube::log::info "  go build ${binary}"
       local outfile=$(kube::golang::output_filename_for_binary "${binary}" "${platform}")
       go build -o "${outfile}" \
         "${goflags[@]:+${goflags[@]}}" \
         -gcflags "${gogcflags}" \
         -ldflags "${goldflags}" \
         "${binary}"
-      kube::log::progress "*"
     done
-    kube::log::progress "\n"
-  else
-    # Use go install.
+  else # Use go install.
+    if [[ "${#statics[@]}" != 0 ]]; then
+      CGO_ENABLED=0 go install -installsuffix static "${goflags[@]:+${goflags[@]}}" \
+        -gcflags "${gogcflags}" \
+        -ldflags "${goldflags}" \
+        "${statics[@]:+${statics[@]}}"
+    fi
     if [[ "${#nonstatics[@]}" != 0 ]]; then
       go install "${goflags[@]:+${goflags[@]}}" \
         -gcflags "${gogcflags}" \
         -ldflags "${goldflags}" \
         "${nonstatics[@]:+${nonstatics[@]}}"
     fi
-    if [[ "${#statics[@]}" != 0 ]]; then
-      CGO_ENABLED=0 go install -installsuffix cgo "${goflags[@]:+${goflags[@]}}" \
-        -gcflags "${gogcflags}" \
-        -ldflags "${goldflags}" \
-        "${statics[@]:+${statics[@]}}"
-    fi
   fi
 
   for test in "${tests[@]:+${tests[@]}}"; do