build: Add -flto to CXXFLAGS

Add -flto to CXXFLAGS to allow build optimization.

Change-Id: Icc7bd996bd512a0d84a35b6a0449f69611a69de1
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/Makefile.am b/Makefile.am
index ebc0f7c..3564cf5 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -19,7 +19,8 @@
 
 libblobcmds_la_CXXFLAGS = \
 	$(SYSTEMD_CFLAGS) \
-	$(PHOSPHOR_LOGGING_CFLAGS)
+	$(PHOSPHOR_LOGGING_CFLAGS) \
+	-flto
 
 nobase_include_HEADERS = \
 	blobs-ipmid/blobs.hpp \