Memory leak in r_io_plugin_init

[Hripsimee]

The r_io_plugin_init function in the libr/io/io_plugin.c source file appears to contain a memory leak. Specifically, memory is allocated using R_NEW0 macro in line 30:

static_plugin = R_NEW0 (RIOPlugin); // line 30

If r_io_plugin_add (io, static_plugin);(line 35) fails to add the allocated memory object to the io, the function will return false. In such a scenario, the allocated memory should be cleaned.

[trufae]

Can you send a pullreq fixing the issue instead of explaining the issue? it's easier to review and you'll get credit