FTBFS: compile errors

Binary package hint: scim

During rebuild testing:

 g++ -DHAVE_CONFIG_H -I. -I.. -I.. -I../src -I.. -I../src -I../intl -DSCIM_DATADIR=\"/usr/share/scim\" -DSCIM_LOCALEDIR=\"/usr/share/locale\" -DSCIM_SYSCONFDIR=\"/etc\" -DSCIM_LIBEXECDIR=\"/usr/lib/scim-1.0\" -DSCIM_ICONDIR=\"/usr/share/scim/icons\" -DSCIM_MODULE_PATH=\"/usr/lib/scim-1.0\" -g -O2 -W -g -O -MT ltdl.lo -MD -MP -MF .deps/ltdl.Tpo -c ltdl.cpp -fPIC -DPIC -o .libs/ltdl.o
ltdl.cpp: In function 'int scim::foreach_dirinpath(const char*, const char*, int (*)(char*, void*, void*), void*, void*)':
ltdl.cpp:2601: warning: comparison between signed and unsigned integer expressions
ltdl.cpp:2610: warning: comparison between signed and unsigned integer expressions
ltdl.cpp: In function 'int scim::try_dlopen(scim::lt_dlhandle_struct**, const char*)':
ltdl.cpp:3054: warning: comparison between signed and unsigned integer expressions
ltdl.cpp: In function 'scim::lt_dlhandle_struct* scim::lt_dlopenext(const char*)':
ltdl.cpp:3376: error: invalid conversion from 'const char*' to 'char*'
ltdl.cpp: In function 'int scim::lt_dlpath_insertdir(char**, char*, const char*)':
ltdl.cpp:3906: warning: comparison between signed and unsigned integer expressions
make[3]: *** [ltdl.lo] Error 1
make[3]: Leaving directory `/build/buildd/scim-1.4.9/src'