Fix Travis-CI build & simplify Makefile & fix README

[hoijui]

see commits for details

[petar]

This looks good. Thank you. The only issue is that syscall.Dup3 does not compile on my machine:
go version go1.12.4 darwin/amd64

To solve this issue, could you add a separate sigpanic_save_panic_trace.go for darwin and linux, perhaps?

[hoijui]

Did that (I think).

[hoijui]

ah.. I just saw that there are 4 arm archs:

• arm
• armbe
• arm64
• arm64be

reference

would I have to define all of them in the +build coment, or does arm stand for all of them?
@ericvh Can you please test if this code still compiles for you?

Edit: It shoul'd work for arm64 now too

[hoijui]

as it is now, syscall.Dup3 will only be used on ARM archs, so for you it will still use syscall.Dup2. The latest commit adds windows and OSX builds to Travis-CI, and they compile fine.