Add -flto to CXXFLAGS

Per openbmc/openbmc#3364, adding -flto to CXX flags
in order to reduce overall library and binary sizes.

Ref: https://gcc.gnu.org/wiki/LinkTimeOptimization

Change-Id: I435596a2e0b134f5220bc9521568354fe9338a79
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
1 file changed