BUILD: makefile: Fix install(1) handling for OpenBSD/NetBSD/Solaris/AIX

Add a new INSTALL variable to allow overridiing the flags passed to
install(1). install(1) on OpenBSD/NetBSD/Solaris/AIX does not support
the -v flag. With the new INSTALL variable and handling only use the
-v flag with the Linux targets.
1 file changed