Generate position-independent code

Libraries generally need position-independent code.  For simplicity, we enable
it globally, even for non-libary code.

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
libca-cas: Call freeaddrinfo after getaddrinfo

Without this patch, there's a memory leak for every call to ca_cas_connect().

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
libca-cas: Don't send NUL byte in GET request

Prior to this commit, a NUL byte was appended to the command and transmitted,
even though we're using newline terminated commands.

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>