[Libguestfs] build failures due to missing rpl_optarg

[Olaf Hering]

For some reason 1.20.2 fails to link in openSuSE 11.4 and older, 1.20.1 did not
have this issue.

...
   CCLD     libguestfs-test-tool
 libguestfs_test_tool-test-tool.o: In function `main':
 test-tool.c:(.text+0x11f): undefined reference to `rpl_getopt_long'
 test-tool.c:(.text+0x170): undefined reference to `rpl_optarg'
 test-tool.c:(.text+0x281): undefined reference to `rpl_optarg'
 test-tool.c:(.text+0x2b2): undefined reference to `rpl_optarg'
 test-tool.c:(.text+0x2ea): undefined reference to `rpl_optarg'
 test-tool.c:(.text+0xd7e): undefined reference to `rpl_perror'
 test-tool.c:(.text+0xd96): undefined reference to `rpl_perror'
 test-tool.c:(.text+0xdcb): undefined reference to `rpl_perror'
 test-tool.c:(.text+0xe97): undefined reference to `rpl_perror'
 collect2: ld returned 1 exit status
 make[2]: *** [libguestfs-test-tool] Error 1
...

Olaf