Custome built dladdr() for AIX.

Implemented a stripped down dladdr()-implementation using AIX' own
loadquery()-function. Following the SGI example in the same code, the
DL_info only has the dli_fname member. As the scope of
dlfcn_pathbyaddr() is the filename, this implementation does not
consider archive members, which can be dlopen()ed in AIX.
Added DATA segment checking to catch ptrgl virtual addresses.

Added test case for DSO_dsobyaddr(), but only for DSO_DLFCN.
Added PIC-flag to aix*-cc build targets.

Signed-off-by: Matthias Kraft <makr@gmx.eu>

Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5626)