cmake: pass an extra #define to test files built to process input files
cmake: pass an extra #define to test files built to process input files

This will let us combine test.c and test-file.c.

Signed-off-by: Josef 'Jeff' Sipek <a620f141433c70aa9e43778305a6c68cbfadfb25@josefsipek.net>

jeffpc/libjeffpc,jeffpc/libjeffpc,jeffpc/libjeffpc,jeffpc/libjeffpc