[PATCH] perf: fix Makefile check for libdward

[Stephane Eranian <eranian@google.com>]

On Ubuntu 9.10, the elfutils/libdw package is 0.141, yet it is
not sufficient to compile util/probe-finder.c as it uses a type,
namely Dwarf_CFI, which is introduced sometime after version 0.141.

This patch updates the libdwarf test in the Makefile to check
for the definition of Dwarf_CFI. If is is not there, the test
fails and dwarf support is disabled.

It is not clear to me which version introduces Dwarf_CFI,
thus I adjusted the version message to 0.142, could be more
recent.

Signed-off-by: Stephane Eranian <eranian@google.com>

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index a9281cc..992bce7 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -508,7 +508,7 @@ PERFLIBS = $(LIB_FILE)
 -include config.mak
 
 ifndef NO_DWARF
-ifneq ($(shell sh -c "(echo '\#include <dwarf.h>'; echo '\#include <libdw.h>'; echo '\#include <version.h>'; echo '\#ifndef _ELFUTILS_PREREQ'; echo '\#error'; echo '\#endif'; echo 'int main(void) { Dwarf *dbg; dbg = dwarf_begin(0, DWARF_C_READ); return (long)dbg; }') | $(CC) -x c - $(ALL_CFLAGS) -I/usr/include/elfutils -ldw -lelf -o $(BITBUCKET) $(ALL_LDFLAGS) $(EXTLIBS) "$(QUIET_STDERR)" && echo y"), y)
+ifneq ($(shell sh -c "(echo '\#include <dwarf.h>'; echo '\#include <libdw.h>'; echo '\#include <version.h>'; echo '\#ifndef _ELFUTILS_PREREQ'; echo '\#error'; echo '\#endif'; echo 'int main(void) { Dwarf *dbg; Dwarf_CFI *cfi; dbg = dwarf_begin(0, DWARF_C_READ); return (long)dbg; }') | $(CC) -x c - $(ALL_CFLAGS) -I/usr/include/elfutils -ldw -lelf -o $(BITBUCKET) $(ALL_LDFLAGS) $(EXTLIBS) "$(QUIET_STDERR)" && echo y"), y)
 	msg := $(warning No libdw.h found or old libdw.h found or elfutils is older than 0.142, disables dwarf support. Please install new elfutils-devel/libdw-dev);
 	NO_DWARF := 1
 endif # Dwarf support