* fix SIGSEGV problem
- reproducable with gda-test program
  - without db2profile: ibmdb2 connection_open, on next connection_open
  with any provider during resolving get_plugin_name with any providerplugin,
    core1.log (bt libdl: dlopen)
    
  - with db2profile: all providers processed successfully,
  when gda-test is terminating
    core2.log (bt libc6: __libc_start_main)

  - rm -f $prefix/lib/libgda/providers/libgda-ibmdb2.*: no coredump/SIGSEGV

* implement queries
  - implement recordsets
  - implement types
