Added xbps_get_pkg_plist_dict_from_repo().

This function will fetch a requested plist file in a binary
package matching its 'pkgname' object by searching in repository pool.

This works in any kind of repository, local and remote. Some code
was Taken from NetBSD's pkg_install HEAD. Oh, and it's on-the-fly!
doesn't need to download the binpkg first!

--HG--
extra : convert_revision : xtraeme%40gmail.com-20091125020936-7uf2ncrf1692c5hz

lib/Makefile

@@ -18,6 +18,7 @@ OBJS +=	configure.o cmpver.o depends.o download.o fexec.o findpkg.o
 OBJS +=	humanize_number.o orphans.o plist.o purge.o register.o remove.o
 OBJS +=	repository.o requiredby.o sha256.o sortdeps.o state.o
 OBJS +=	sync_remote_pkgidx.o unpack.o util.o pkgmatch.o
+OBJS +=	repository_plist.o
 
 .PHONY: all
 all: libfetch libxbps.so libxbps.a