perf tools: Fix /etc config related installation

Fix missing /etc/bash_completion.d directory creation, otherwise
the installation fails miserably on systems that don't have bash
completion installed yet or on specific target:

	   $ make DESTDIR=/tmp/junk-perf O=/tmp/pbuild -C tools/perf/ install
	   ...
	   install -m 755 bash_completion /tmp/junk-perf/etc/bash_completion.d/perf
	   install: cannot create regular file
	   `/tmp/junk-perf/etc/bash_completion.d/perf': No such file or directory
	   make: *** [install] Error 1
	   make: Leaving directory `/opt/sw/ahern/perf.git/tools/perf'

Also use sysconfdir variable instead of the hardcoded /etc to handle
overriden conf directory.
Reported-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1344522713-27951-4-git-send-email-fweisbec@gmail.comSigned-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Makefile

@@ -700,6 +700,7 @@ perfexecdir_SQ = $(subst ','\'',$(perfexecdir))
 template_dir_SQ = $(subst ','\'',$(template_dir))
 htmldir_SQ = $(subst ','\'',$(htmldir))
 prefix_SQ = $(subst ','\'',$(prefix))
+sysconfdir_SQ = $(subst ','\'',$(sysconfdir))
 
 SHELL_PATH_SQ = $(subst ','\'',$(SHELL_PATH))
 
@@ -951,7 +952,8 @@ install: all
 	$(INSTALL) scripts/python/Perf-Trace-Util/lib/Perf/Trace/* -t '$(DESTDIR_SQ)$(perfexec_instdir_SQ)/scripts/python/Perf-Trace-Util/lib/Perf/Trace'
 	$(INSTALL) scripts/python/*.py -t '$(DESTDIR_SQ)$(perfexec_instdir_SQ)/scripts/python'
 	$(INSTALL) scripts/python/bin/* -t '$(DESTDIR_SQ)$(perfexec_instdir_SQ)/scripts/python/bin'
-	$(INSTALL) -m 755 bash_completion $(DESTDIR_SQ)/etc/bash_completion.d/perf
+	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(sysconfdir_SQ)/bash_completion.d'
+	$(INSTALL) bash_completion '$(DESTDIR_SQ)$(sysconfdir_SQ)/bash_completion.d/perf'
 
 install-python_ext:
 	$(PYTHON_WORD) util/setup.py --quiet install --root='/$(DESTDIR_SQ)'