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>
diff --git a/Documentation/perf_counter/exec_cmd.h b/Documentation/perf_counter/exec_cmd.h
new file mode 100644
index 0000000..effe25e
--- /dev/null
+++ b/Documentation/perf_counter/exec_cmd.h
@@ -0,0 +1,13 @@
+#ifndef PERF_EXEC_CMD_H
+#define PERF_EXEC_CMD_H
+
+extern void perf_set_argv_exec_path(const char *exec_path);
+extern const char *perf_extract_argv0_path(const char *path);
+extern const char *perf_exec_path(void);
+extern void setup_path(void);
+extern const char **prepare_perf_cmd(const char **argv);
+extern int execv_perf_cmd(const char **argv); /* NULL terminated */
+extern int execl_perf_cmd(const char *cmd, ...);
+extern const char *system_path(const char *path);
+
+#endif /* PERF_EXEC_CMD_H */