libaio: don't disable linking to the system libraries
For some reason that I don't understand (a decade-old attempt at optimisation?)
libaio disables linkage to the system libraries. Enabling fortify means linking
to the system libraries, so remove the existing addition of -lc for x86 (the
problem also happens on at least PPC) and just link to the system libraries on
all platforms.
Also remove the sed of src/Makefile as the build not respecting LDFLAGS has been
fixed upstream.
Signed-off-by: Ross Burton <ross.burton@intel.com>
