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.
Configure: Split the usecrosscompile section from the to/from/run section

Beyond organization, this also makes sure that usecrosscompile is
always set to undef if we're not cross-compiling, which enables
code to realibly use $Config{usecrosscompile} to check for a
cross-compiling perl.
Configure: When cross-compiling, look for *-gcc* instead of *-*-gcc

Ditto with g++. This allows us to use, for example, ntox86-gcc or
x86_64-w64-mingw32-g++.exe to cross-compile, and have Configure detect
most things automatically.
Fix two Configure tests when targethost is set
Configure: No need to skip the byteorder test when cross-compiling.

This skip was added in 2001, but under the current model there's no
real reason to skip it.
Configure: Use $ccflags in $checkccflag

This is potentially counterproductive, but it's vital when
using -Dsysroot, as otherwise the results are entirely
unreliable.
Configure: Add $run to two tests
Configure: Don't skip the alignbytes test when crosscompiling
Configure: If using targetarch, the computed binaries should stick
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
Add missing $run prefix to some Configure tests
Store the targetdir, targethost from Configure in config.sh for later.
Configure: Set to/from/run scripts if targethost is passed

Do this regardless of whether we are cross compiling
add an escape for when targethost is not defined but usecrosscompile is.

See http://www.nntp.perl.org/group/perl.perl5.porters/2012/12/msg196443.html
"Cross-building and Makefile.SH", which explains the reasoning for this.
fix the ability to use targethost when defined.
Update AUTHORS and MANIFEST to appease test_porting
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
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