compile error in SoText2.c

[mike allerhand <michael.allerhand@ed.ac.uk>]

Compiling inventor-2.1.5-6 under RH7.0 with
gcc 2.96-54 stopped at SoText.c after a few warnings
and an Error 1:
cannot convert 'const char **' to 'char **' for argument 2
to iconv(...).