Checking if your kit is complete...
Looks good
Writing Makefile for Digest::Hashcash
cp Hashcash.pm blib/lib/Digest/Hashcash.pm
/home/cpanrun/ia64-lp64/build/5.6.1/bin/perl -I/home/cpanrun/ia64-lp64/build/5.6.1/lib/5.6.1/IA64.ARCHREV_0-thread-multi-64all -I/home/cpanrun/ia64-lp64/build/5.6.1/lib/5.6.1 /home/cpanrun/ia64-lp64/build/5.6.1/lib/5.6.1/ExtUtils/xsubpp  -typemap /home/cpanrun/ia64-lp64/build/5.6.1/lib/5.6.1/ExtUtils/typemap Hashcash.xs > Hashcash.xsc && mv Hashcash.xsc Hashcash.c
gcc -c  -DUSE_REENTRANT_API -D_POSIX_C_SOURCE=199506L -D_HPUX_SOURCE -mlp64 -L/lib/hpux64 -DUINT32_MAX_BROKEN -fPIC -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -O   -DVERSION=\"0.03\" -DXS_VERSION=\"0.03\" -fPIC -I/home/cpanrun/ia64-lp64/build/5.6.1/lib/5.6.1/IA64.ARCHREV_0-thread-multi-64all/CORE  Hashcash.c
Hashcash.xs:7:20: stdint.h: No such file or directory
make: *** [Hashcash.o] Error 1