fix -I flag paths when building out-of-tree

The current build logic assumes the build dir is directly under the
source dir.  This fails if the build and source trees are completely
different paths.  So use a full path to the source dir rather than a
relative one so that it works in all states.

BUG=chromium-os:33327
TEST=`cros_run_unit_tests --board x86-alex -p crash-reporter` still works

Change-Id: I0e6b4c257cbef5879cb67e8692e3082bbb5fb2d5
Reviewed-on: https://gerrit.chromium.org/gerrit/29577
Reviewed-by: Ben Chan <benchan@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/crash_reporter/Makefile b/crash_reporter/Makefile
index 51f18e8..648308f 100644
--- a/crash_reporter/Makefile
+++ b/crash_reporter/Makefile
@@ -20,7 +20,7 @@
 PC_CFLAGS := $(shell $(PKG_CONFIG) --cflags $(PC_DEPS))
 PC_LIBS := $(shell $(PKG_CONFIG) --libs $(PC_DEPS))
 
-CPPFLAGS += -I.. -I$(SYSROOT)/usr/include/google-breakpad $(PC_CFLAGS)
+CPPFLAGS += -I$(SRC)/.. -I$(SYSROOT)/usr/include/google-breakpad $(PC_CFLAGS)
 LDLIBS = -lgflags $(PC_LIBS)