perf_counter tools: add in basic glue from Git

First very raw version at having a central 'perf' command and
a list of subcommands:

  perf top
  perf stat
  perf record
  perf report
  ...

This is done by picking up Git's collection of utility functions,
and hacking them to build fine in this new environment.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/perf_counter/.gitignore

@@ -0,0 +1,179 @@
+GIT-BUILD-OPTIONS
+GIT-CFLAGS
+GIT-GUI-VARS
+GIT-VERSION-FILE
+git
+git-add
+git-add--interactive
+git-am
+git-annotate
+git-apply
+git-archimport
+git-archive
+git-bisect
+git-bisect--helper
+git-blame
+git-branch
+git-bundle
+git-cat-file
+git-check-attr
+git-check-ref-format
+git-checkout
+git-checkout-index
+git-cherry
+git-cherry-pick
+git-clean
+git-clone
+git-commit
+git-commit-tree
+git-config
+git-count-objects
+git-cvsexportcommit
+git-cvsimport
+git-cvsserver
+git-daemon
+git-diff
+git-diff-files
+git-diff-index
+git-diff-tree
+git-difftool
+git-difftool--helper
+git-describe
+git-fast-export
+git-fast-import
+git-fetch
+git-fetch--tool
+git-fetch-pack
+git-filter-branch
+git-fmt-merge-msg
+git-for-each-ref
+git-format-patch
+git-fsck
+git-fsck-objects
+git-gc
+git-get-tar-commit-id
+git-grep
+git-hash-object
+git-help
+git-http-fetch
+git-http-push
+git-imap-send
+git-index-pack
+git-init
+git-init-db
+git-instaweb
+git-log
+git-lost-found
+git-ls-files
+git-ls-remote
+git-ls-tree
+git-mailinfo
+git-mailsplit
+git-merge
+git-merge-base
+git-merge-index
+git-merge-file
+git-merge-tree
+git-merge-octopus
+git-merge-one-file
+git-merge-ours
+git-merge-recursive
+git-merge-resolve
+git-merge-subtree
+git-mergetool
+git-mergetool--lib
+git-mktag
+git-mktree
+git-name-rev
+git-mv
+git-pack-redundant
+git-pack-objects
+git-pack-refs
+git-parse-remote
+git-patch-id
+git-peek-remote
+git-prune
+git-prune-packed
+git-pull
+git-push
+git-quiltimport
+git-read-tree
+git-rebase
+git-rebase--interactive
+git-receive-pack
+git-reflog
+git-relink
+git-remote
+git-repack
+git-repo-config
+git-request-pull
+git-rerere
+git-reset
+git-rev-list
+git-rev-parse
+git-revert
+git-rm
+git-send-email
+git-send-pack
+git-sh-setup
+git-shell
+git-shortlog
+git-show
+git-show-branch
+git-show-index
+git-show-ref
+git-stage
+git-stash
+git-status
+git-stripspace
+git-submodule
+git-svn
+git-symbolic-ref
+git-tag
+git-tar-tree
+git-unpack-file
+git-unpack-objects
+git-update-index
+git-update-ref
+git-update-server-info
+git-upload-archive
+git-upload-pack
+git-var
+git-verify-pack
+git-verify-tag
+git-web--browse
+git-whatchanged
+git-write-tree
+git-core-*/?*
+gitk-wish
+gitweb/gitweb.cgi
+test-chmtime
+test-ctype
+test-date
+test-delta
+test-dump-cache-tree
+test-genrandom
+test-match-trees
+test-parse-options
+test-path-utils
+test-sha1
+test-sigchain
+common-cmds.h
+*.tar.gz
+*.dsc
+*.deb
+git.spec
+*.exe
+*.[aos]
+*.py[co]
+config.mak
+autom4te.cache
+config.cache
+config.log
+config.status
+config.mak.autogen
+config.mak.append
+configure
+tags
+TAGS
+cscope*