Set building of shared libraries on QNX to defatul OFF


configure.in:
  -Libtool forgets to pass the -q64 and -X64 flags to "nm" and "xlc_r" when building
  for 64-bit on AIX. Add some hacks before we create libtool that fixes this.
  This test should be integrated into autoconf/libtool
  
  -Set default to not build shared librarues on QNX. When building libmysqlclient and libmysqlclient_r
  so many objects are passed to libtool that sh propably runs out of stack  and segfaults.