Although errors reported in standard libraries almost always have to do with other config issues have you had a look at what is in your stdlib.h from lines say 150-160. I see a short #ifdef __USE_ISOC99 block (although you may have something else) It is not impossible (although it is very very very unlikely) that there is a syntax error in that block. You could add and #undef __USE_ISOC99 to skip it and see if it makes.

If that fails as I expect it will the quickest option is probably to install Perl 5.6.2 or a 5.8 and try the compile with your new perl. You can have parallel installs. (thisperl) Makefile.PL determines which perl is used when you make, so you can install a new perl anywhere you like and just put a link to /usr/bin/perl562 for example.