make.bash: if CC is not set, and gcc doesn't exist, try clang/clang++. This should make Go build without setting CC and CXX on newer FreeBSDs.
make.bash: if CC is not set, and gcc doesn't exist, try clang/clang++.
This should make Go build without setting CC and CXX on newer FreeBSDs.

LGTM=iant
R=golang-codereviews, dave, gobot, iant
CC=golang-codereviews
https://codereview.appspot.com/89230045

d0f/go-zh,bryanxu/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc,webfd/go-zh,sanjosh/sanjos100-tipc,webfd/go-zh,sanjosh/sanjos100-tipc,webfd/go-zh,bryanxu/go-zh,d0f/go-zh,sanjosh/sanjos100-tipc,bryanxu/go-zh,d0f/go-zh,d0f/go-zh,d0f/go-zh,sanjosh/sanjos100-tipc,d0f/go-zh,d0f/go-zh,bryanxu/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc,webfd/go-zh,bryanxu/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc,d0f/go-zh,sanjosh/sanjos100-tipc,bryanxu/go-zh,webfd/go-zh,bryanxu/go-zh,bryanxu/go-zh