package: Makefile: fix perf target bug

Specify --git-dir when building perf targets to allow out-of-tree
builds using O=<build-dir>.

The shell command in `git archive' had to be modified to allow proper
file name expansion of the files listed in MANIFEST.
Signed-off-by: matt mooney <mfm@muteddisk.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/package/Makefile

@@ -118,10 +118,12 @@ perf-tar=perf-$(KERNELVERSION)
 
 quiet_cmd_perf_tar = TAR
       cmd_perf_tar = \
-git archive --prefix=$(perf-tar)/ HEAD^{tree}                       \
-	$$(cat $(srctree)/tools/perf/MANIFEST) -o $(perf-tar).tar;  \
+git --git-dir=$(srctree)/.git archive --prefix=$(perf-tar)/         \
+	HEAD^{tree} $$(cd $(srctree);                               \
+		       echo $$(cat $(srctree)/tools/perf/MANIFEST)) \
+	-o $(perf-tar).tar;                                         \
 mkdir -p $(perf-tar);                                               \
-git rev-parse HEAD > $(perf-tar)/HEAD;                              \
+git --git-dir=$(srctree)/.git rev-parse HEAD > $(perf-tar)/HEAD;    \
 tar rf $(perf-tar).tar $(perf-tar)/HEAD;                            \
 rm -r $(perf-tar);                                                  \
 $(if $(findstring tar-src,$@),,                                     \