[release-branch.go1.10] all: merge master into release-branch.go1.10, for go1.10rc2

This adds the go get security fix.

* 1dcb5836 cmd/go: accept only limited compiler and linker flags in #cgo directives

Change-Id: Ib2caf2039d2cefabe3afa0bb4dcc4c0dc8d664ff
diff --git a/VERSION b/VERSION
new file mode 100644
index 0000000..a251e05
--- /dev/null
+++ b/VERSION
@@ -0,0 +1 @@
+go1.10rc1
\ No newline at end of file