Add support for stripped host installation

Add option --[no-]strip to strip host binaries from symbols. Symbols usually
don't make sense for end users but waste a lot of space. If --strip option
is specified than host applications will be installed using target
install-strip, instead of default install. GDB and CGEN are not affected
because they do not support this install target and I don't want to
workaround this by stripping them manually from the script. Stripping is
optional, by default toolchain is with debug symbols.