libpldmresponder : add missing include path

The libpldmresponder Makefile.am needs to add top_srcdir to the include
path to enable out-of-tree builds. This way the code can continue to
include something like "libpldm/foo.h".

Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>
Change-Id: If4fa6f1fdac3395dfb389989f18d5de4d259de46
diff --git a/libpldmresponder/Makefile.am b/libpldmresponder/Makefile.am
index dca2be6..1b82777 100644
--- a/libpldmresponder/Makefile.am
+++ b/libpldmresponder/Makefile.am
@@ -14,6 +14,8 @@
 	$(CODE_COVERAGE_CXXFLAGS) \
 	$(SDBUSPLUS_CFLAGS)
 
-libpldmresponder_la_CPPFLAGS = $(CODE_COVERAGE_CPPFLAGS)
+libpldmresponder_la_CPPFLAGS = \
+	$(CODE_COVERAGE_CPPFLAGS) \
+	-I$(top_srcdir)