xbps-src: infrastructure changes required for "nonfree" keyword in tmpls.

- The chroot target now execs masterdir/bin/xbps-shell to set up correct envvars.
- 2 pkgs are now in nonfree repo: adobe-flash-plugin and jre.
- Renamed some vars in xbps-src to be in uppercase, notably XBPS_MACHINE.
- make-repoidx target now creates the index for all "known" directories specified
  via XBPS_PACKAGESDIR: XBPS_MACHINE, noarch, and nonfree/XBPS_MACHINE.

srcpkgs/glibc/template

@@ -45,8 +45,8 @@ do_build()
 
 	# Build with -mno-tls-direct-seg-refs to avoid performance problems
 	# with Xen on x86 32bit.
-	if [ "${xbps_machine}" = "i686" ]; then
-		cflags="-mno-tls-direct-seg-refs -march=${xbps_machine%%-*}"
+	if [ "${XBPS_MACHINE}" = "i686" ]; then
+		cflags="-mno-tls-direct-seg-refs -march=${XBPS_MACHINE%%-*}"
 		cflags="$cflags -mtune=generic"
 	fi
 	cflags="$XBPS_CFLAGS $cflags"
@@ -85,7 +85,7 @@ do_install()
 	replace_interpreter bash ${DESTDIR}/usr/bin/ldd
 
 	# On x86_64, add dynamic linker's 32bit version to ldd.
-	if [ "$xbps_machine" = "x86_64" ]; then
+	if [ "$XBPS_MACHINE" = "x86_64" ]; then
 		rtldlist="/lib/ld-linux.so.2 /lib/ld-linux-x86-64.so.2"
 		sed -i "s|^RTLDLIST.*$|RTLDLIST=\"$rtldlist\"|" \
 			${DESTDIR}/usr/bin/ldd