Fix BDB and SQLite build problems

libgda currently doesn't build with autotools on FreeBSD because of the following two problems:

1. BDB_CURRENT_BUILDDIR is not defined for autotools build.

gmake[2]: Entering directory '/home/lantw44/gnome/build/libgda/providers/bdb'
  CC       gda-bdb-test.o
/home/lantw44/gnome/source/libgda/providers/bdb/gda-bdb-test.c:31:10: warning: initializing 'GList *' (aka 'struct _GList *') with an expression of type 'const GList *' (aka 'const struct _GList *') discards qualifiers
      [-Wincompatible-pointer-types-discards-qualifiers]
  GList *events = gda_connection_get_events (cnc);
         ^        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/lantw44/gnome/source/libgda/providers/bdb/gda-bdb-test.c:185:30: error: use of undeclared identifier 'BDB_CURRENT_BUILDDIR'
  dbp = g_file_new_for_path (BDB_CURRENT_BUILDDIR);
                             ^
1 warning and 1 error generated.

2. FreeBSD libc does not define uint type:

gmake[2]: Entering directory '/home/lantw44/gnome/build/libgda/libgda/sqlite'
clang -B/home/lantw44/.local/bin -o mkkeywordhash  /home/lantw44/gnome/source/libgda/libgda/sqlite/mkkeywordhash.c
/home/lantw44/gnome/source/libgda/libgda/sqlite/mkkeywordhash.c:264:12: error: use of undeclared identifier 'uint'; did you mean 'int'?
                assert( (uint) p->len < sizeof(p->zOrigName) );
                         ^~~~
                         int
/usr/include/assert.h:54:21: note: expanded from macro 'assert'
#define assert(e)       ((e) ? (void)0 : __assert(__func__, __FILE__, \
                          ^
/home/lantw44/gnome/source/libgda/libgda/sqlite/mkkeywordhash.c:264:18: error: expected ')'
                assert( (uint) p->len < sizeof(p->zOrigName) );
                               ^
/home/lantw44/gnome/source/libgda/libgda/sqlite/mkkeywordhash.c:264:3: note: to match this '('
                assert( (uint) p->len < sizeof(p->zOrigName) );
                ^
/usr/include/assert.h:54:20: note: expanded from macro 'assert'
#define assert(e)       ((e) ? (void)0 : __assert(__func__, __FILE__, \
                         ^
/home/lantw44/gnome/source/libgda/libgda/sqlite/mkkeywordhash.c:264:11: error: reference to overloaded function could not be resolved; did you mean to call it?
                assert( (uint) p->len < sizeof(p->zOrigName) );
                        ^~~~~~
/usr/include/assert.h:54:21: note: expanded from macro 'assert'
#define assert(e)       ((e) ? (void)0 : __assert(__func__, __FILE__, \
                          ^
3 errors generated.