flag_enabled(): declare is local by default - remove it

[MilhouseVH]

Reviewing the flag_enabled() code that sets the flag variable (ie. PKG_SPEED_TARGET_ENABLED etc.) I noticed the declared variables were not actually visible outside of the flag_enabled() function.

From help declare:

    When used in a function, `declare' makes NAMEs local, as with the `local'
    command.  The `-g' option suppresses this behavior.

Adding the -g option would allow the variables to become visible to the caller, meaning this code would work as intended.

However, as the variables are not currently used and I suspect will almost certainly never be used, I'd like to remove support for the declared variables as it complicates the function unnecessarily, could potentially result in a hard-to-debug variable name collision, and is just additional overhead.

[InuSasha]

not build tested, but sounds reasonable.