msys2-runtime: attempt to use makepkg's split debuginfo feature

To avoid additional changes to msys2-runtime's build (such as changing flags due to 'debug' being set), I didn't set debug at the top level of the PKGBUILD, but rather just in the msys2-runtime package.  This means that makepkg didn't attempt to actually package an msys2-runtime-debug package, so I included the files in msys2-runtime-devel.

msys2-runtime/PKGBUILD

@@ -4,7 +4,7 @@
 pkgbase=msys2-runtime
 pkgname=('msys2-runtime' 'msys2-runtime-devel')
 pkgver=3.5.3
-pkgrel=2
+pkgrel=3
 pkgdesc="Cygwin POSIX emulation engine"
 arch=('x86_64')
 url="https://www.cygwin.com/"
@@ -220,6 +220,7 @@ package_msys2-runtime() {
   pkgdesc="Posix emulation engine for Windows"
   conflicts=('catgets' 'libcatgets' 'msys2-runtime-3.4' 'msys2-runtime-3.5')
   replaces=('catgets' 'libcatgets' 'msys2-runtime-3.5')
+  options=('debug' 'strip')
 
   mkdir -p "${pkgdir}"/usr
   cp -rf "${srcdir}"/dest/usr/bin "${pkgdir}"/usr/
@@ -245,4 +246,7 @@ package_msys2-runtime-devel() {
   rm -fr "${pkgdir}"/usr/include/rpc/
 
   cp -rLf "${srcdir}"/dest/usr/${CHOST}/lib "${pkgdir}"/usr/
+
+  # debug info created during 'strip' by makepkg
+  cp -rLf "${pkgdir}/../msys2-runtime-debug/"* "${pkgdir}"
 }