Fix runtime libraries find and installation
* m4/gpg4win.m4(GPG4WIN_RUNTIME_LIBRARY): New. Helper for runtime libraries. Searches more locations. * configure.ac: Use above and add libwinpthread-1.dll dependency * src/inst-gpg4win.nsi: Install libwinpthread-1.dll. Move runtime libs from pub to top level install dir. * src/uninst-gpg4win.nsi: Uninstall runtime libs from their new location.
This also fixes the problem that libraries were not reported as
missing when no other missing tools were found missing.
(cherry picked from commit 03550750d4f581515b0349889ff8d1894943f3a6)