If you are using HP-UX compiler, you can use the following command (which has been tested with cc B.11.11.04):

CC=cc CXX=aCC CFLAGS=+DD64 CXXFLAGS=+DD64 ./configure \
    --with-extra-character-set=complex

You can ignore any errors of the following type:

aCC: warning 901: unknown option: `-3': use +help for online
documentation

If you get the following error from configure, verify that you do not have the path to the K&R compiler before the path to the HP-UX C and C++ compiler:

checking for cc option to accept ANSI C... no
configure: error: MySQL requires an ANSI C compiler (and a C++ compiler).
Try gcc. See the Installation chapter in the Reference Manual.

Another reason for compile failure is that you did not define the +DD64 flags as just described.