typer: Remove VxWorks

A comment referred to vxworks and was thusly removed
Merge branch 'maint'

Conflicts:
	lib/diameter/autoconf/vxworks/sed.general
	xcomp/README.md
Merge tag 'OTP_R15B02'

The R15B02 release
Implement ./otp_build configure --enable-silent-rules

With silent rules, the output of make is less verbose and compilation
warnings are easier to spot. Silent rules are disabled by default and
can be disabled or enabled at will by make V=0 and make V=1.
Prepare release