Allow parallel copy/link in pg_upgrade

This patch implements parallel copying/linking of files by tablespace
using the --jobs option in pg_upgrade.
Don't attempt to write recovery.conf when -R is not specified

Fixes segmentation fault during regular use.

Fujii Masao
Properly install ecpg_compat and pgtypes libraries on msvc

JiangGuiqing
Detect Windows perl linkage parameters in configure script.

This means we can now construct a configure test for the library
presence. Previously these parameters were only figured out at
build time in plperl's GnuMakefile.
Add explicit configure-time checks for perl.h and libperl.so.

Although most platforms seem to package Perl in such a way that these files
are present even in basic Perl installations, Debian does not.  Hence, make
an effort to fail during configure rather than build if --with-perl was
given and these files are lacking.  Per gripe from Josh Berkus.
Test linking libperl.so using only Perl's required libraries.

It appears that perl_embed_ldflags should already mention all the libraries
that are required by libperl.so itself.  So let's try the test link with
just those and not the other LIBS we've found up to now.  This should
more nearly reproduce what will happen when plperl is linked, and perhaps
will fix buildfarm member okapi's problem.