Fix: resolve symbol namespacing. Ticket #8068

The hidden GCC attribute is better suited here instead of prefixing each
symbol with torsocks_* in order to avoid polluting the library namespace
for no benefits.

Four symbols are made static since they were not used outside of their C
file. This automatically fix the exported symbol for these calls.

Fixes #8068

Signed-off-by: David Goulet <dgoulet@ev0ke.net>