It will rebase any *.{dll,so,oct} except usr/bin/msys-2.0.dll. Note it
requires the rebase db to be present, so essentially it requires
rebaseall to have been run (probably at install).
This can never have worked since "paths-from-unix-to-windows" was never installed/packaged.
I'm also not quite sure what the initial goal was based on the git history, so remove it for now.
The implicit `.` (current working directory) in PATH can cause the script to
call a wrong dash/bash if present alongside the installer.
Fixes https://sourceforge.net/p/msys2/tickets/141/
* upgrade some broken packages
* correct some broken urls/checksums
* use secure urls where possible
* use stable url for ncurses
* some whitespace fixes
Remaining md5sums either didn't download or
didn't pass checksum tests.
