At least one version of the standard GNU C Library already contains a definition for struct name_list (on my system, this is in /usr/include/inet/netgroup.h). This file is also indirectly included when building source/utils/smbtree.c.
smbtree.c also tries to define a struct name_list, on line 33 of a vanilla 3.2.4 source tree and thus fails the build.
Renaming the structure type name (I used "smb_name_list") allows the build to proceed.
Fixed in all git-trees. Thanks !