lib/ldb/tests: include stdint.h before cmocka.h

lib/ldb/tests: include stdint.h before cmocka.h

This fix the following build failures:

[2466/3864] Linking bin/default/lib/ldb/ldbmodify
In file included from /home/buildroot/autobuild/instance-0/output-1/host/opt/ext-toolchain/lib/gcc/mips64el-buildroot-linux-uclibc/5.5.0/include/stdint.h:9:0,
                 from ../../lib/tevent/tevent.h:31,
                 from ../../lib/ldb/include/ldb.h:51,
                 from ../../lib/ldb/tests/test_ldb_dn.c:25:
/home/buildroot/autobuild/instance-0/output-1/host/mips64el-buildroot-linux-uclibc/sysroot/usr/include/stdint.h:122:27: error: conflicting types for 'uintptr_t'
 typedef unsigned long int uintptr_t;
                           ^
In file included from ../../lib/ldb/tests/test_ldb_dn.c:23:0:
/home/buildroot/autobuild/instance-0/output-1/host/mips64el-buildroot-linux-uclibc/sysroot/usr/include/cmocka.h:132:28: note: previous declaration of 'uintptr_t' was here
       typedef unsigned int uintptr_t;
                            ^

In file included from /home/buildroot/autobuild/instance-0/output-1/host/opt/ext-toolchain/lib/gcc/mips64el-buildroot-linux-uclibc/5.5.0/include/stdint.h:9:0,
                 from ../../lib/tevent/tevent.h:31,
                 from ../../lib/ldb/tests/ldb_key_value_test.c:48:
/home/buildroot/autobuild/instance-0/output-1/host/mips64el-buildroot-linux-uclibc/sysroot/usr/include/stdint.h:122:27: error: conflicting types for 'uintptr_t'
 typedef unsigned long int uintptr_t;
                           ^
In file included from ../../lib/ldb/tests/ldb_key_value_test.c:43:0:
/home/buildroot/autobuild/instance-0/output-1/host/mips64el-buildroot-linux-uclibc/sysroot/usr/include/cmocka.h:132:28: note: previous declaration of 'uintptr_t' was here
       typedef unsigned int uintptr_t;
                            ^

Fixes:
 - http://autobuild.buildroot.org/results/9507739b3d5d51024ee9c60b74c2f85d5004e7e2

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14218

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Reviewed-by: Uri Simchoni <uri@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>