Revamp usecrosscompile section.
Use sysroot for libpath/incpath if set.
Set to/from/run scripts if targethost is passed, regardless of whether we are cross compiling
Set appropriate flags for linux or linux-like systems.

This means that osnames that look like *linux*, like linux-androideabi
or linux-gnueabihf are treated like linux systems.
Add missing $run prefix to some Configure tests
Stop using $run for anything other than testing compiled tests in Configure.

When cross-compiling we want to run miniperl etc on the compile host, not the test target
No xconfig.h is produced when cross-compiling, we have a normal config.h
Stop using Config{run} to check the version of (mini)perl we are running
Build host miniperl and generate_uudmap binaries when cross compiling, for local use
Run all the miniperl calls remotely, not via RUN
Fix Makefile so that host dir is removed in make distclean
Configure: Remove "was file copied" check using run-ssh

This doesn't seem to be of much use.
Introduce $targetport to allow running on a non-standard ssh port

Such as when using user networking on qemu and redirecting a local port
to the emulator ssh
Re-organise the creation of Config.pm to allow $^O to be "osname" from config.sh, instead of miniperl's $^O.

This is necessary when cross-compiliing, as we use a host (mini)perl to run configpm for the target arch.
add an escape for when targethost is not defined but usecrosscompile is.
fix the ability to use targethost when defined.
Update AUTHORS and MANIFEST to appease test_porting
Use the system perl for RUN_PERL, if we are cross compiling, and we found one.

Note we can only substitute the system perl for scripts that do not require Config
as it complains about non-matching Perl versions.
Setup $^O to be the target os when building Core.
This allows the correct hints files to be loaded when building modules
write_buildcustomize.pl: Take an osname parameter

This means that write_buildcustomize.pl no longer depends on
Config to get osname, which eliminates a circular dependency
in the Makefiles.
Makefile.SH: Updated the lib/buildcustomize.pl rule for cross-compilation builds
Amend pod_lib.pl (for installperl) to work with miniperl (no dynamic loading available)

This is to allow cross-compilation builds to run installperl using a host miniperl instead of the build Perl binary.