lib/misc/depcheck: check (R)DEPEND
use "test -h", not "test -L"
lib/die, die__minimal(): accept **DIE
defsym: $EX_ERR
build-scripts/buildvars: change BUILD_WORKDIR location
CC: improve shlibcc search

This allows to execute the CC wrapper script from "anywhere".
doc: add build-scripts dir to overview
use $(...) instead of backticks

for improved readability (also for consistency because $(...) allows sane
usage of nested commands).