dropwatch is not built with the linker flags as defined in the redhat-rpm-config package. I tried to set LDFLAGS in dropwatch-1.4-20.fc28, but the variable is not properly passed down to the actual linker command line, hence this bug report.
Looks like LDFLAGS in the makefile was using LDFLAGS= rather than LDFLAGS+= Should be fixed in release -21
This bug appears to have been reported against 'rawhide' during the Fedora 28 development cycle. Changing version to '28'.
Confirmed as fixed in dropwatch-1.4-22.fc28.