This is a port of https://golang.org/cl/18150 to the gccgo runtime.
The previous behaviour of installing the signal handlers in a separate
thread meant that Go initialization raced with non-Go initialization if
the non-Go initialization also wanted to install signal handlers. Make
installing signal handlers synchronous so that the process-wide behavior
is predictable.
Reviewed-on: https://go-review.googlesource.com/19494
From-SVN: r233393
These changes permit using the go tool from the upcoming Go
1.5 release with -buildmode=c-archive to build gccgo code into
an archive file that can be linked with a C program.
From-SVN: r222594
Ian Lance Taylor