s3/rpcclient: Fix bad (and illegal) func cast

s3/rpcclient: Fix bad (and illegal) func cast

../../source3/rpcclient/cmd_samr.c: In function ‘cmd_samr_get_usrdom_pwinfo’:
../../librpc/ndr/libndr.h:219:76: error: cast between incompatible function types from ‘void (*)(struct ndr_print *, const char *, uint32_t)’ {aka ‘void (*)(struct ndr_print *, const char *, unsigned int)’} to ‘void (*)(struct ndr_print *, const char *, const void *)’ [-Werror=cast-function-type]
 #define NDR_PRINT_STRUCT_STRING(ctx, type, p) ndr_print_struct_string(ctx, (ndr_print_fn_t)ndr_print_ ##type, #p, p)
                                                                            ^
../../source3/rpcclient/cmd_samr.c:2646:4: note: in expansion of macro ‘NDR_PRINT_STRUCT_STRING’
    NDR_PRINT_STRUCT_STRING(mem_ctx,

Signed-off-by: Noel Power <noel.power@suse.com>
Reviewed-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Fri May 10 02:26:02 UTC 2019 on sn-devel-184