Extend Linker Debug Support

Adding support to trace the library calls and hooks, to make it easier to find missing hooks depending on the library used by hybris.

Run example:
root@ubuntu-phablet:~# export HYBRIS_LINKER_DEBUG=1
root@ubuntu-phablet:~# export HYBRIS_LINKER_STDOUT=1
root@ubuntu-phablet:~# test_sensors 
[ HYBRIS: initializing library 'libhardware.so']
[     0 linking libhardware.so ]
`liblog.so` is not a prelinked library
    0 mapped library 'liblog.so' to 401ca000 via kernel allocator.
[ HYBRIS: initializing library 'liblog.so']
[     0 linking liblog.so ]
`libc.so` is not a prelinked library
    0 mapped library 'libc.so' to 40242000 via kernel allocator.
[ HYBRIS: initializing library 'libc.so']
[     0 linking libc.so ]
`libdsyscalls.so` is not a prelinked library
    0 mapped library 'libdsyscalls.so' to 40327000 via kernel allocator.
[ HYBRIS: initializing library 'libdsyscalls.so']
[     0 linking libdsyscalls.so ]
HYBRIS: 'libdsyscalls.so' checking hooks for sym 'dlsym'
HYBRIS: 'libdsyscalls.so' checking hooks for sym 'dlopen'
HYBRIS: 'libdsyscalls.so' checking hooks for sym 'dlerror'
HYBRIS: 'libdsyscalls.so' checking hooks for sym 'dlclose'
HYBRIS: 'libdsyscalls.so' checking hooks for sym '__libc_postfini'
HYBRIS: 'libdsyscalls.so' checking hooks for sym '__cxa_begin_cleanup'
HYBRIS: 'libdsyscalls.so' checking hooks for sym '__cxa_type_match'
HYBRIS: 'libdsyscalls.so' checking hooks for sym '__libc_postfini'
HYBRIS: 'libdsyscalls.so' checking hooks for sym '__cxa_call_unexpected'
....