This makes the type in line with string(3) functions and eliminates some
compiler warnings.
Also update the related bencode data type.
Change-Id: I7ef4024f4b5a0f737b3dbe03bcd078032395bce6
Rename test suites from *-test.c to test-*.c as the former is
conflicting with the file name pattern of the build tests, which are
listed in .gitignore.
Change-Id: I8779fac492510c0996bdcb2c6250c07536fe3b63