Alexander GQ Gerasiov
Fix linking under -Wl,--as-needed
Ubuntu's linker uses -Wl,--as-needed by default, which causes ppswatch
to fail to link because of the order of options on the commandline. Add
-lm to LDLIBS instead of LDFLAGS, which will cause it to be passed in
the right order.
Author: Steve Langasek <firstname.lastname@example.org>