QPID-5079: slim down exported symbols in official API libraries
QPID-5079: Added link map file to cut the number of symbols right down
WIP: (fixup) add operators to export list
WIP: (fixup) Only do gcc import/export thing with gcc compatible compilers
WIP: Remove unecessary bits of exception
QPID-5079: Add some stuff to check the symbols exported
WIP: Get --as-needed working correctly, tidyup mess with NSS libraries