kmodloader: support duplicate module names and aliases

kmodloader: support duplicate module names and aliases

Allow duplicate keys in the 'modules' avl tree, fixing an indirect memory
leak observed during testing. Given avl keys treat '_' and '-' equally,
some modules may have aliases duplicating their own names under this
mapping, so skip adding these redundant avl tree nodes in alloc_module().

With the above support, update 'modinfo' to print details for all modules
matching the cmdline name, rather than only the first. This is the expected
behaviour and consistent with upstream. The behaviour of other kmodloader
applets, such as boot-time loading or modprobe, remains unchanged.

Signed-off-by: Tony Ambardar <itugrok@yahoo.com>