If you are building 64-bit binaries, you must pass the define ODBC64. Demoodbc provides an example of this. See the installed file demoodbc.txt and The demoodbc Application for details.

You must also include the -xarch=v9 compiler switch if you are building 64-bit binaries. For example, to build demoodbc, you would use: 

CC -mt –DODBC64 -xarch=v9 -o demoodbc -I../include demoodbc.c -L../lib -lodbc –lCrun