perf tools: Remove some unused functions

Without the bloated cplus_demangle from binutils, i.e building with:

$ make NO_DEMANGLE=1 O=~acme/git/build/perf -j3 -C tools/perf/ install

Before:

   text	   data	    bss	    dec	    hex	filename
 471851	  29280	4025056	4526187	 45106b	/home/acme/bin/perf

After:

[acme@doppio linux-2.6-tip]$ size ~/bin/perf
   text	   data	    bss	    dec	    hex	filename
 446886	  29232	4008576	4484694	 446e56	/home/acme/bin/perf

So its a 5.3% size reduction in code, but the interesting part is in the git
diff --stat output:

 19 files changed, 20 insertions(+), 1909 deletions(-)

If we ever need some of the things we got from git but weren't using, we just
have to go to the git repo and get fresh, uptodate source code bits.

Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/exec_cmd.c

@@ -116,7 +116,7 @@ void setup_path(void)
 	strbuf_release(&new_path);
 }
 
-const char **prepare_perf_cmd(const char **argv)
+static const char **prepare_perf_cmd(const char **argv)
 {
 	int argc;
 	const char **nargv;