This commit adds a new wrapper, random_get_bytes(), that is currently
defined to use os_get_random() as is. The places using
random_get_bytes() depend on the returned value being strong random
number, i.e., something that is infeasible for external device to
figure out. These values are used either directly as a key or as
nonces/challenges that are used as input for key derivation or
authentication.
The remaining direct uses of os_get_random() do not need as strong
random numbers to function correctly.
Clean up the internal TLS implementation by removing conditional
build blocks for (mostly) EAP-FAST specific functionality. This
will increase the size a big for non-EAP-FAST builds, but is quite
helpful in making src/tls/libtls.a with single build options. If
the potential size reduction is considered significant in the future,
this can be reconsider with a more library compatible way (e.g.,
external file with registration function, etc.).
In addition, start ordering header file includes to be in more
consistent order: system header files, src/utils, src/*, same
directory as the *.c file.
