community/aerc: remove LDFLAGS workaround
The variable naming was fixed in https://git.sr.ht/~rjarry/aerc/commit/247c6c74380a9e56527ec0a87965a39142ffc213
The variable naming was fixed in https://git.sr.ht/~rjarry/aerc/commit/247c6c74380a9e56527ec0a87965a39142ffc213