lua-eco: fix LUA_ECO_CRASH_BACKTRACE recursive dependency

lua-eco: fix LUA_ECO_CRASH_BACKTRACE recursive dependency

LUA_ECO_CRASH_BACKTRACE declared "depends on PACKAGE_lua-eco" while
lua-eco's DEPENDS carries "+LUA_ECO_CRASH_BACKTRACE:libunwind", which the
generator turns into "select libunwind if LUA_ECO_CRASH_BACKTRACE". kconfig
then sees lua-eco and the symbol depending on each other:

  error: recursive dependency detected!
    symbol LUA_ECO_CRASH_BACKTRACE depends on PACKAGE_lua-eco
    symbol PACKAGE_lua-eco depends on LUA_ECO_CRASH_BACKTRACE

Drop the redundant guard; the option only affects lua-eco's own build, so
nothing is pulled in when lua-eco itself is not selected.

Fixes: https://github.com/openwrt/packages/pull/30098#issuecomment-5113528752
Signed-off-by: Alexandru Ardelean <redacted>