Fix libfan_la_CXXFLAGS

The libfan_la_CXXFLAGS was incorrectly defined as empty by a typo, fix
it.
Then specify gcc-ar gcc-ranlib for link time optimization, otherwise the
static library will get link error.

Tested: Verify the build is OK in CI, local build, and SDK build.
Resolves openbmc/phosphor-fan-presence#11

Change-Id: I17c83b9927a796f8928a71688c1640d1a602a108
Signed-off-by: Lei YU <mine260309@gmail.com>
2 files changed