callgrind: fix build with srcdir != builddir

Thanks to Diego 'Flameeyes' Pettenò for noting and providing the patch



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@6751 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/callgrind/Makefile.am b/callgrind/Makefile.am
index 234fc2d..dd15eb0 100644
--- a/callgrind/Makefile.am
+++ b/callgrind/Makefile.am
@@ -34,7 +34,7 @@
 CALLGRIND_SOURCES_PPC32 = ../cachegrind/cg-ppc32.c
 CALLGRIND_SOURCES_PPC64 = ../cachegrind/cg-ppc64.c
 
-CALLGRIND_CFLAGS_COMMON = -I../cachegrind
+CALLGRIND_CFLAGS_COMMON = -I$(top_srcdir)/cachegrind
 
 clincludedir = $(includedir)/valgrind
 clinclude_HEADERS = \